Java 工具类整理汇总

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记录下来一些常用的，或用过的，会持续更新 …

XML、JSON 字符串互转

2021-01-29 10:21:54

有时候，我们需要“xmlStr -> jsonStr -> xmlStr”

1）、导入依赖

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<!-- https://mvnrepository.com/artifact/cn.hutool/hutool-all -->
<dependency>
	<groupId>cn.hutool</groupId>
	<artifactId>hutool-all</artifactId>
	<version>5.5.7</version>
</dependency>

2）、代码示例

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import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;


//2021/1/29 上午10:05 xmlStr -> jsonStr -> xmlStr
public static void main(String[] args) {
    //<sites>
    //    <site>
    //        <name>菜鸟教程</name>
    //        <url>www.runoob.com</url>
    //    </site>
    //    <site>
    //        <name>Google</name>
    //        <url>www.google.com</url>
    //    </site>
    //    <site>
    //        <name>淘宝</name>
    //        <url>www.taobao.com</url>
    //    </site>
    //</sites>


    //<sites><site><name>菜鸟教程</name><url>www.runoob.com</url></site><site><name>Google</name><url>www.google.com</url></site><site><name>淘宝</name><url>www.taobao.com</url></site></sites>
    String xmlStr = "<sites><site><name>菜鸟教程</name><url>www.runoob.com</url></site><site><name>Google</name><url>www.google.com</url></site><site><name>淘宝</name><url>www.taobao.com</url></site></sites>";


    // xmlStr -> jsonStr
    String jsonStr = JSONUtil.xmlToJson(xmlStr).toString();
    //{"sites":{"site":[{"url":"www.runoob.com","name":"菜鸟教程"},{"url":"www.google.com","name":"Google"},{"url":"www.taobao.com","name":"淘宝"}]}}


    // jsonStr -> xmlStr
    String xmlStr1 = JSONUtil.toXmlStr(new JSONObject(jsonStr));
    //<sites><site><url>www.runoob.com</url><name>菜鸟教程</name></site><site><url>www.google.com</url><name>Google</name></site><site><url>www.taobao.com</url><name>淘宝</name></site></sites>

}

Ftp

2021-01-21 16:01

1）、导入依赖（hutool 封装的 ftp 工具依赖 commons-net）

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<!-- https://mvnrepository.com/artifact/commons-net/commons-net -->
<dependency>
	<groupId>commons-net</groupId>
	<artifactId>commons-net</artifactId>
	<version>3.7.2</version>
</dependency>
<!-- https://mvnrepository.com/artifact/cn.hutool/hutool-all -->
<dependency>
	<groupId>cn.hutool</groupId>
	<artifactId>hutool-all</artifactId>
	<version>5.5.7</version>
</dependency>

2）、代码示例

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import cn.hutool.core.io.IoUtil;
import cn.hutool.extra.ftp.Ftp;
import org.apache.commons.net.ftp.FTPFile;
import java.io.InputStream;


//2021-01-21 16:01 测试 ftp
public static void main(String[] args) throws Exception {
	Ftp ftp = new Ftp("121.127.241.19", 21, "ftp", "ftp");
	//上传，下载
	//ftp.upload("/opt/upload", FileUtil.file("e:/test.jpg"));
	//ftp.download("/opt/upload", "test.jpg", FileUtil.file("e:/test2.jpg"));

	//查看文件列表
	FTPFile[] ftpFiles = ftp.lsFiles("/");
	FTPFile ftpFile = ftpFiles[0];
	String name = ftpFile.getName();// a


	// 上传：会把原有的覆盖
	String uploadStr = "我是愤怒1";
	ftp.upload("/", "test_upload", IoUtil.toUtf8Stream(uploadStr));


	// 读取数据
	InputStream inputStream = ftp.getClient().retrieveFileStream("/a");
	String read = IoUtil.readUtf8(inputStream);

	//ftp inputStream处理完毕，记得 reply，防止下次获取 inputStream == null
	ftp.getClient().getReply();

	//关闭连接
	ftp.close();
}

ExceptionUtil

2022-01-22 21:45:08

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package com.alibaba.nacos.common.utils;

import java.io.ByteArrayOutputStream;
import java.io.PrintStream;

/**
 * Common methods for exception.
 *
 * @author nkorange
 * @since 1.2.0
 */
public class ExceptionUtil {
    
    /**
     * Represents an empty exception, that is, no exception occurs, only a constant.
     */
    public static final Exception NONE_EXCEPTION = new RuntimeException("");
    
    public static String getAllExceptionMsg(Throwable e) {
        Throwable cause = e;
        StringBuilder strBuilder = new StringBuilder();
        
        while (cause != null && !StringUtils.isEmpty(cause.getMessage())) {
            strBuilder.append("caused: ").append(cause.getMessage()).append(";");
            cause = cause.getCause();
        }
        
        return strBuilder.toString();
    }
    
    public static Throwable getCause(final Throwable t) {
        final Throwable cause = t.getCause();
        if (Objects.isNull(cause)) {
            return t;
        }
        return cause;
    }
    
    public static String getStackTrace(final Throwable t) {
        if (t == null) {
            return "";
        }
        
        final ByteArrayOutputStream out = new ByteArrayOutputStream();
        final PrintStream ps = new PrintStream(out);
        t.printStackTrace(ps);
        ps.flush();
        return new String(out.toByteArray());
    }
}