Simplify Java programming magic weapon, make work more efficient

This is the 31st day of my participation in the August Text Challenge.More challenges in August

The previous article covered some of the components provided by the HuTool project, but there is much more to HuTool than that. Next, I’ll show you some of the convenience tools that HuTool provides.

If you have not read the previous article, it does not matter, it does not affect your understanding of the following content, but for the benefit of those who have directly read the second article, it is necessary to introduce HuTool.

Add the following to the project’s PM.xml dependencies:

<dependency>
    <groupId>cn.hutool</groupId>
    <artifactId>hutool-all</artifactId>
    <version>5.0.7</version>
</dependency>
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For non-Maven projects, you can download the JAR package from Baidu and import it.

StrUtil

This is a utility class that handles strings.

There’s nothing more to say about strings, but let’s take a look at the methods it provides.

1, hasBlank, hasEmpty

Both methods are used to determine if a string is empty, as shown in the following code:

@Test
// Determine if the string is empty
public void hasBlankOrhasEmptyTest(a){
    String str1 = "";
    String str2 = "";
    System.out.println(StrUtil.hasBlank(str1));
    System.out.println(StrUtil.hasBlank(str2));
    System.out.println(StrUtil.hasEmpty(str1));
    System.out.println(StrUtil.hasEmpty(str2));
}
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Running results:

true
true
false
true
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Note that while both methods are used to determine whether a given string is empty, the hasEmpty method can only determine null and empty strings (“”), and the hasBlank method treats invisible characters as empty. For example, in the above program, for str1, whose value is an invisible character (space), the hasEmpty method does not empty the string, whereas the hasBlank method treats the string as empty. But for STR2, there is no ambiguity between the two methods and it is uniformly considered as null.

RemovePrefix, removeSuffix

These methods are used to remove the specified prefix and suffix from a string, respectively.

Look at the code:

    @Test
    // Removes the specified prefix and suffix from the string
    public void removePrefixOrremoveSuffixTest(a){
        String str1 = "test.jpg";
        // remove the suffix
        System.out.println(StrUtil.removeSuffix(str1,".jpg"));
        // Remove the specified prefix
        System.out.println(StrUtil.removePrefix(str1,"test"));
    }
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Running results:

test
.jpg
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3, sub

This method is an improvement on the subString method provided by the JDK. Remember what the JDK subString method does?

It is used to intercept a string and return the corresponding subString by the given index. Since the traditional subString method has too many problems, what is the problem? Look at the code:

    @Test
    public void subTest(a){
        String str = "hello world";
        System.out.println(str.substring(0.12));
    }
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In this program, the length of the string STR is 11, but the truncation of the string length is 12, obviously the index crossed the boundary, but sometimes we can make this error, but it is not a good way to run the error. To do this, StrUtil provides a sub method, which takes into account all sorts of considerations and handles them accordingly. It also supports a negative index, -1 for the last character, which is Python style.

The code is as follows:

    @Test
    // Intercepts a string
    //index starts at 0 and ends with -1
    // If from and to are the same, return ""
    // If from or to is negative, the value of the absolute value is greater than the length of the string, the value of from is 0, and the value of to is length
    // Swap from and to if from is greater than to in the corrected index
    public void subTest(a){
        String str = "hello world";
        System.out.println(StrUtil.sub(str,0.12));
    }
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Even if your index position is extremely wrong, the sub method can easily handle it. The result of this program is:

hello world
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4, the format

This method is used to format text. You can use a string template instead of string concatenation.

    @Test
    // Format the text
    public void formatTest(a){
        String str = "{} The blackbird flies {}";
        String formatStr = StrUtil.format(str, "Thousand"."Never");
        System.out.println(formatStr);
    }

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Running results:

Not a bird over hundreds of peaksCopy the code

This method uses {} as placeholders and then replaces the placeholders in the order of the arguments, so be careful where the arguments are placed. If you put the “absolute” word first, the result will be different.

    @Test
    // Format the text
    public void formatTest(a){
        String str = "{} The blackbird flies {}";
        String formatStr = StrUtil.format(str, "Never"."Thousand");
        System.out.println(formatStr);
    }

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Running results:

Mountain birds fly thousandsCopy the code

URLUtil

This utility class is dedicated to working with urls.

1, the url

This method converts a string to a URL object as follows:

    @Test
    // Convert a string to a URL object
    public void urlTest(a) {
        URL url = URLUtil.url("http://localhost:8080/name=zhangsan&age=20");
        // Get the domain name part of the URL, keeping only the protocol in the URL
        URI uri = URLUtil.getHost(url);
        System.out.println(uri);
    }

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Running results:

http://localhost

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2, getURL

This method is used to get a URL, usually when absolute paths are used, and the code is as follows:

    @Test
    // Get the URL, often used when absolute paths are used
    public void getURLTest(a) {
        URL url = URLUtil.getURL(FileUtil.file("URLUtilTest.java"));
        System.out.println(url.toString());
    }

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Running results:

file:/C:/Users/Administrator/Desktop/ideaworkspace/HuTool/out/production/HuTool/URLUtilTest.java

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This method gets the absolute path of the file by name, which is handy in scenarios where absolute paths are used.

3, normalize

This method is used to standardize URL links as follows:

    @Test
    // Standardize URL links
    public void normalizeTest(a) {
        String url = "www.baidu.com\\example\\test/a";
        String newUrl = URLUtil.normalize(url);
        System.out.println(newUrl);
    }

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Running results:

http://www.baidu.com/example/test/a

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This method automatically completes and formats links without the http:// header.

4, getPath

This method is used to get the path part of the string in the URL link, for example:

    @Test
    // Get the path section
    public void getPathTest(a) {
        String url = "http://localhost/search? name=abc&age=20";
        String pathStr = URLUtil.getPath(url);
        System.out.println(pathStr);
    }

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Running results:

/search

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ObjectUtil

In our everyday use, there are methods that are generic for objects and do not discriminate between objects. For these methods, Hutool encapsulates ObjectUtil.

1, equal

This method is used to compare whether two objects are equal under two conditions:

obj1 == null && obj2 == null
obj1.equal(obj2)

If one of these conditions is met, the two objects are equal, as follows:

    @Test
    // Compare whether two objects are equal.
    // There are two identical conditions, one of which can be satisfied:
    //obj1 == null && obj2 == null obj1.equals(obj2)
    public void equalTest(a) {
        Object obj = null;
        Object obj2 = null;
        boolean equal = ObjectUtil.equal(obj, obj2);
        System.out.println(equal);
    }

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Running results:

true

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2, length,

This method is used to calculate the length of the object passed in, or if it is a string; If a collection is passed in, the collection size is computed; The length method automatically calls the length calculation method of the corresponding type.

    @Test
    The collection class calls its size function, the array calls its length property, and other traversable objects count the length
    // The following types are supported: CharSequence Map Iterator Enumeration Array
    public void lengthTest(a) {
        String str = "hello world";
        List<Integer> list = Arrays.asList(1.2.3.4.5.6);
        System.out.println(ObjectUtil.length(str));
        System.out.println(ObjectUtil.length(list));
    }

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Running results:

11
6

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3, the contains

This method is used to determine whether the specified element exists in a given object, as follows:

    @Test
    // Whether the object contains elements
    The supported object types are String Collection Map Iterator Enumeration Array
    public void containsTest(a) {
        List<Integer> list = Arrays.asList(1.2.3.4.5.6);
        boolean flag = ObjectUtil.contains(list, 1);
        System.out.println(flag);
    }

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Running results:

true

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4, isBasicType

This method is used to determine whether a given object is a primitive type, both wrapped and unwrapped, with the following code:

    @Test
    // Whether it is a basic type, including wrapped type and unwrapped type
    public void isBasicTypeTest(a){
        String str = "hello";
        int num = 100;
        boolean flag = ObjectUtil.isBasicType(str);
        boolean flag2 = ObjectUtil.isBasicType(num);
        System.out.println(flag);
        System.out.println(flag2);
    }

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Running results:

false
true

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ReflectUtil

Reflection mechanism is the core of Java, Java framework implementation uses a lot of reflection, HuTool for Java reflection to do some packaging.

1, getMethods

This method is used to get all the methods in a class, including those in its parent class.

    @Test
	// Get a list of all methods in a class, including those in its parent class
    public void getMethodsTest(a) {
        Method[] methods = ReflectUtil.getMethods(Object.class);
        for(Method method : methods) { System.out.println(method.getName()); }}Copy the code

Running results:

finalize
wait
wait
wait
equals
toString
hashCode
getClass
clone
notify
notifyAll
registerNatives

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2, getMethod

This method is used to get the specified method of a class as follows:

    @Test
    // Gets the specified method of a class
    public void getMethodsTest(a) {
        Method method = ReflectUtil.getMethod(Object.class, "getClass");
        System.out.println(method);
    }

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Running results:

public final native java.lang.Class java.lang.Object.getClass()

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* * 3, newInstance * *

This method instantiates an object using the Class type of the Class, as follows:

    @Test
    // instantiate the object
    public void newInstanceTest(a) {
        Object obj = ReflectUtil.newInstance(Object.class);
        boolean flag = ObjectUtil.isNull(obj);
        System.out.println(flag);
    }

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Running results:

false

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4, invoke

This method is used to execute the methods in the object, with the following code:

    @Test
    // Execute method
    public void invokeTest(a) {
        ArrayList list = ReflectUtil.newInstance(ArrayList.class);
        ReflectUtil.invoke(list,"add".1);
        System.out.println(list);
    }

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Running results:

[1]

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The second parameter is the name of the method to execute, and the third parameter is the method parameter to execute.

ClipboardUtil

This is a clipboard utility class to simplify operations on the clipboard, which may be used in some scenarios.

1, getStr

This method is used to retrieve the contents of the clipboard. For example, if you select a section of the content and copy it with the mouse, this method can obtain the copied content, the code is as follows:

    @Test
    // Get text content from the clipboard
    public void getStrTest(a) {
        String  str = ClipboardUtil.getStr();
        System.out.println(str);
    }

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Running results:

String  str = ClipboardUtil.getStr();

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2, setStr

This method sets the contents of the clipboard, that is, you copy the contents of the clipboard by setting the specified string to the clipboard as follows:

    @Test
    // Sets the clipboard text content
    public void setStrTest(a) {
        String  str = ClipboardUtil.getStr();
        System.out.println(str);
        ClipboardUtil.setStr("hello world");
        String str2 = ClipboardUtil.getStr();
        System.out.println(str2);
    }

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Running results:

String  str = ClipboardUtil.getStr();
hello world

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There are methods to get pictures, set pictures and so on, we can experience.

ClassUtil

This class mainly encapsulates some reflection methods, making it easier to call.

1, getShortClassName

This method is used to get the short format of the class name as follows:

    @Test
    // Get the short format of the class name
    public void getShortClassNameTest(a){
        String shortClassName = ClassUtil.getShortClassName("com.wwj.hutool.test.ObjectUtilTest");
        System.out.println(shortClassName);
    }

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Running results:

c.w.h.t.ObjectUtilTest

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2, getPackage

Gets the package name of the specified class as follows:

    @Test
    // Gets the package name of the specified class
    public void getPackageTest(a){
        String packageName = ClassUtil.getPackage(ObjectUtilTest.class);
        System.out.println(packageName);
    }

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Running results:

com.wwj.hutool.test

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3, scanPackage

This method is at the heart of the utility class. It is a method that scans resources under a package and is used in Spring for dependency injection as follows:

    @Test
    // Scan for resources under packets
    public void scanPackageTest(a){ Set<Class<? >> classes = ClassUtil.scanPackage("com.wwj.hutool.test");
        for (Class<?> aclass : classes) {
            System.out.println(aclass.getName());
        }
    }

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Running results:

com.wwj.hutool.test.URLUtilTest
com.wwj.hutool.test.StrUtilTest
com.wwj.hutool.test.ObjectUtilTest

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This method takes a package name as an argument and scans all classes under the specified package. You can also filter out the specified class by passing in a ClassFilter object.

4, getJavaClassPaths

This method is used to get the ClassPath defined by Java’s system variables.

    @Test
    public void scanPackageTest(a){
        String[] javaClassPaths = ClassUtil.getJavaClassPaths();
        for(String javaClassPath : javaClassPaths) { System.out.println(javaClassPath); }}Copy the code

Running results:

F:\Tool\IntelliJ IDEA 2018.3\lib\idea_rt.jar
F:\Tool\IntelliJ IDEA 2018.3\plugins\junit\lib\junit-rt.jar
F:\Tool\IntelliJ IDEA 2018.3\plugins\junit\lib\junit5-rt.jar
E:\Java\jdk18.. 0 _181\jre\lib\charsets.jar
E:\Java\jdk18.. 0 _181\jre\lib\deploy.jar
......

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RuntimeUtil

This utility class is used to execute command line commands, CMD on Windows and shell on Linux.

Because it’s easy, just post the code:

    @Test
    public void RunTimeUtilTest(a){
        String str = RuntimeUtil.execForStr("ipconfig");
        System.out.println(str);
    }

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Running results:

Windows IP Configuration Ethernet Adapter Ethernet: media status............ : Media disconnected Connection specific DNS suffix....... : Wireless LAN adapter Local connection *1: media status............ : Media disconnected Connection specific DNS suffix....... : wireless LAN adapter Local connection *2: Media status............ : Media is disconnected Connect specific DNS suffix....... : wireless LAN adapter WLAN: Connect specific DNS suffix....... : www.tendawifi.com Local link IPv6 address........ : fe80::830:2d92:1427:a434%17IPv4 address............ :192.168. 0103.Subnet mask............ :255.255255.. 0Default gateway............. :192.168. 01.

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NumberUtil

This is a utility class for mathematical operations. In traditional Java development, you often encounter computations between decimals that can easily lose precision. For accuracy, you often use BigDecimal classes, but converting between them is complicated. For this purpose, HuTool provides the NumberUtil class, which makes mathematical calculations very easy to use.

1. Addition, subtraction, multiplication and division

    @Test
    public void calcTest(a){
        double d = 3.5;
        float f = 0.5 f;
        System.out.println(NumberUtil.add(d,f));/ / add
        System.out.println(NumberUtil.sub(d,f));/ /
        System.out.println(NumberUtil.mul(d,f));/ / by
        System.out.println(NumberUtil.div(d,f));/ / in addition to
    }

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Running results:

4.0
3.0
1.75
7.0

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2. Keep decimals

    @Test
    public void calcTest(a){
        double d = 1234.56789;
        System.out.println(NumberUtil.round(d,2));
        System.out.println(NumberUtil.roundStr(d,3));
    }

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Running results:

1234.57
1234.568

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The round and roundStr methods can be used to preserve decimals. The default mode is round, but you can also pass in the corresponding mode change program.

3. Numerical judgment

NumberUtil provides a series of methods for determining common types of numbers, so it’s easy to skip the code and just look at the method name and what it does.

NumberUtil.isNumberIs it a number?
NumberUtil.isIntegerIs it an integer?
NumberUtil.isDoubleWhether it is a floating point number
NumberUtil.isPrimesWhether it’s prime

4, other

Of course, there are some more common math operations that NumberUtil encapsulates.

NumberUtil.factorialfactorial
NumberUtil.sqrtThe square root
NumberUtil.divisorGreatest common divisor
NumberUtil.multipleLeast common multiple
NumberUtil.getBinaryStrGets the binary string corresponding to the number
NumberUtil.binaryToIntBinary to int
NumberUtil.binaryToLongBinary to long
NumberUtil.compareCompares the size of two values
NumberUtil.toStrNumber to string, automatically and remove redundant zeros after the last decimal point

IdUtil

This utility class is primarily used to generate unique ids.

1. Generate the UUID

    @Test
    public void IdUtilTest(a){
        String uuid = IdUtil.randomUUID();
        String simpleUUID = IdUtil.simpleUUID();
        System.out.println(uuid);
        System.out.println(simpleUUID);
    }

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Running results:

b1e4e753-39b9-4026-8a08-ce9837e15f62
23f1603604694d029bb35c1c03d7aeb1

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The ramdimUUID method produces a UUID with a ‘-‘, while the simpleUUID method produces a UUID without a ‘-‘.

2, the ObjectId

ObjectId is a unique ID generation policy for the MongoDB database. It is a variant of UUID version1.

Hutool against the encapsulates the cn. Hutool. Core. Lang. ObjectId, quickly create method is:

// Generate similar: 5b9e306a4df4f8C54a39fb0c
String id = ObjectId.next();

// Method 2: Start with hutool-4.1.14
String id2 = IdUtil.objectId();

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3, Snowflake

In distributed systems, there are some scenarios where globally unique ids are required, and sometimes we want to use a simpler ID that can be generated in chronological order. Twitter’s Snowflake algorithm is one such generator.

The usage method is as follows:

// Parameter 1 is the terminal ID
// Parameter 2 is the ID of the data center
Snowflake snowflake = IdUtil.createSnowflake(1.1);
long id = snowflake.nextId();

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ZipUtil

In Java, packing and compressing files and folders is a tedious task, and we often introduce Zip4j to do this. But in many cases, the ZIP package in the JDK will do most of the job. ZipUtil is a tool package for java.util.zip, so that the compression and decompression operations can be done in one way, and automatically handle file and directory problems, no longer need to judge the user, compressed files will automatically create files, automatically create a parent directory, greatly simplifying the compression and decompression complexity.

1, Zip,

    @Test
    public void zipUtilTest(a){
        ZipUtil.zip("C:/Users/Administrator/Desktop/test.txt");
    }

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Observe the desktop:Compression succeeded.

Of course, you can also specify the location of the compressed package by passing the path to the zip method as the second parameter.

Multiple file or directory compression. You can select multiple files or directories into a ZIP package:

    @Test
    public void zipUtilTest(a) {
        ZipUtil.zip(FileUtil.file("d:/bbb/ccc.zip"), false,
                FileUtil.file("d:/test1/file1.txt"),
                FileUtil.file("d:/test1/file2.txt"),
                FileUtil.file("d:/test2/file1.txt"),
                FileUtil.file("d:/test2/file2.txt")); }Copy the code

The decompression method is unzip.

2, GZip

Gzip is a widely used compression method for web page delivery, and Hutool also provides its own tool method to simplify the process.

Ziputil. gzip ziputil. gzip ziputil. unGzip ziputil. unGzip ziputil. unzip gzip files

3, Zlib

ZipUtil zlib compression, compressible string, can also be compressed file ZipUtil. UnZlib decompression zlib file

IdCardUtil

In daily development, we mainly verify the ID card in regular mode (digit, number range, etc.), but The Chinese ID card, especially the 18-digit ID card, has strict rules for each bit, and the last bit is the check bit. And in our practical application, the verification of id card should be strict so far. IdcardUtil was born.

IdcardUtil now supports 15-digit and 18-digit ids for mainland China and 10-digit IDS for Hong Kong, Macao and Taiwan.

The main methods in the tool include:

isValidCardVerify your ID card is legitimate
convert15To18Id card 15 digits to 18 digits
getBirthByIdCardFor birthday
getAgeByIdCardFor age
getYearByIdCardGet birthday year
getMonthByIdCardGet birthday month
getDayByIdCardGet birthday day
getGenderByIdCardFor gender
getProvinceByIdCardObtain province

use

String ID_18 = "321083197812162119";
String ID_15 = "150102880730303";

// Whether it is valid
boolean valid = IdcardUtil.isValidCard(ID_18);
boolean valid15 = IdcardUtil.isValidCard(ID_15);

/ / conversion
String convert15To18 = IdcardUtil.convert15To18(ID_15);
Assert.assertEquals(convert15To18, "150102198807303035");

/ / age
DateTime date = DateUtil.parse("2017-04-10");

int age = IdcardUtil.getAgeByIdCard(ID_18, date);
Assert.assertEquals(age, 38);

int age2 = IdcardUtil.getAgeByIdCard(ID_15, date);
Assert.assertEquals(age2, 28);

/ / birthday
String birth = IdcardUtil.getBirthByIdCard(ID_18);
Assert.assertEquals(birth, "19781216");

String birth2 = IdcardUtil.getBirthByIdCard(ID_15);
Assert.assertEquals(birth2, "19880730");

/ / provinces
String province = IdcardUtil.getProvinceByIdCard(ID_18);
Assert.assertEquals(province, "Jiangsu");

String province2 = IdcardUtil.getProvinceByIdCard(ID_15);
Assert.assertEquals(province2, Inner Mongolia);

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The last

This article has just taken a look at some of the tool classes in HuTool. In fact, HuTool is a very nice project that implements a lot of Java operations, making it easy for us to handle some of the more complex things.

For more information about HuTool, you can learn about it yourself.

Simplify Java programming magic weapon, make work more efficient

StrUtil

URLUtil

ObjectUtil

ReflectUtil

ClipboardUtil

ClassUtil

RuntimeUtil

NumberUtil

IdUtil

ZipUtil

IdCardUtil

The last

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