一、简要概述

在Linux中curl是一个利用URL规则在命令行下工作的文件传输工具，可以说是一款很强大的http命令行工具。它支持文件的上传和下载，是综合传输工具，但按传统，习惯称curl为下载工具。它被广泛应用在Unix、多种Linux发行版中，并且有DOS和Win32、Win64下的移植版本。

借助JAVA的shell脚本执行方法，我们可以在curl命令支持下，封装出一个代码精简且功能丰富的HTTP调用工具类。

二、封装过程

1. 引入依赖

pom.xml

<dependency>
	<groupId>org.slf4j</groupId>
	<artifactId>slf4j-simple</artifactId>
	<version>2.0.16</version>
</dependency>
<dependency>
	<groupId>org.apache.commons</groupId>
	<artifactId>commons-lang3</artifactId>
	<version>3.5</version>
</dependency>
<dependency>
	<groupId>commons-io</groupId>
	<artifactId>commons-io</artifactId>
	<version>2.15.0</version>
</dependency>
<dependency>
	<groupId>org.projectlombok</groupId>
	<artifactId>lombok</artifactId>
	<version>1.18.12</version>
	<scope>provided</scope>
</dependency>
<dependency>
	<groupId>org.junit.jupiter</groupId>
	<artifactId>junit-jupiter-engine</artifactId>
	<version>5.5.2</version>
</dependency>

2. 定义脚本执行类

ShellExecutor.java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.SystemUtils;

import lombok.extern.slf4j.Slf4j;

@Slf4j
public class ShellExecutor
{
    /**
     * execute命令
     * 
     * @param command
     * @throws IOException
     */
    public static void exec(String command)
    {
        try
        {
            log.info("✈✈✈✈✈ WILL EXECUTE COMMAND: {} ✈✈✈✈✈", command);
            String[] cmd = SystemUtils.IS_OS_WINDOWS ? new String[] {"cmd", "/c", command} : new String[] {"/bin/sh", "-c", command};
            Runtime.getRuntime().exec(cmd);
        }
        catch (IOException e)
        {
            log.error(e.getMessage(), e);
        }
    }
    
    /**
     * execute命令
     * 
     * @param command
     * @return 执行结果
     * @throws IOException
     */
    public static String execute(String command)
    {
        try
        {
            log.info("✈✈✈✈✈ WILL EXECUTE COMMAND: {} ✈✈✈✈✈", command);
            String[] cmd = SystemUtils.IS_OS_WINDOWS ? new String[] {"cmd", "/c", command} : new String[] {"/bin/sh", "-c", command};
            List<String> resultList = new ArrayList<>();
            try (BufferedReader br = new BufferedReader(new InputStreamReader(Runtime.getRuntime().exec(cmd).getInputStream())))
            {
                String line;
                while ((line = br.readLine()) != null)
                {
                    resultList.add(line);
                }
            }
            return StringUtils.join(resultList, System.lineSeparator());
        }
        catch (IOException e)
        {
            log.error(e.getMessage(), e);
            return "";
        }
    }
}

上面的代码中，我们我们定义了2个方法：
exec 适用于不带返回值或返回值为非String类型的接口调用。

execute带String类返回值，适用于restful接口json数据返回值的接口调用。

三、单元测试

import java.io.File;
import java.io.IOException;
import java.nio.charset.StandardCharsets;

import org.apache.commons.io.FileUtils;
import org.junit.jupiter.api.Test;

import lombok.extern.slf4j.Slf4j;

@Slf4j
public class ShellExecutorTest
{
    @Test
    public void test001()
        throws IOException
    {
        String response = ShellExecutor.execute("curl https://00fly.online/upload/data.json");
        log.info(response);
    }
    
    @Test
    public void test002()
        throws IOException
    {
        ShellExecutor.exec("curl -X GET -H  \"Accept:image/jpeg\" -H  \"Content-Type:application/x-www-form-urlencoded\" \"https://00fly.online/upload/2019/02/201902262129360274AKuFZcUfip.jpg\" --output cat.jpg");
    }
    
    @Test
    public void test003()
        throws IOException
    {
        String response = ShellExecutor.execute("curl https://00fly.online/upload/data.json");
        FileUtils.writeStringToFile(new File("test.json"), response, StandardCharsets.UTF_8, false);
    }
    
    @Test
    public void test004()
        throws IOException
    {
        ShellExecutor.exec("curl https://00fly.online/upload/data.json  -o test.json");
        ShellExecutor.exec("curl https://00fly.online/upload/data.json  --output test2.json");
    }
    
    @Test
    public void test005()
        throws IOException
    {
        // 模仿浏览器、伪造referer
        String response = ShellExecutor
            .execute("curl -A \"Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.0)\" -e \"blog.csdn.net\" \"https://blog.csdn.net/community/home-api/v1/get-business-list?page=1&size=20&businessType=lately&noMore=false&username=qq_16127313\"");
        log.info(response);
    }
    
    @Test
    public void test006()
        throws IOException
    {
        // 伪造referer
        String response = ShellExecutor.execute("curl -e \"blog.csdn.net\" \"https://blog.csdn.net/community/home-api/v1/get-business-list?page=1&size=20&businessType=lately&noMore=false&username=qq_16127313\"");
        log.info(response);
    }
}

四、其他资源

更多CURL命令高级用法，请参考curl文档

另外，在线接口文档knife4j、httpbin等已经集成了等价curl命令，各位可以拷贝测试自行探索。

注意：如果需要将包含此工具的工程打包成docker镜像，一定要在镜像构建文件Dockerfile中安装curl

#安装curl
RUN sed -i 's/dl-cdn.alpinelinux.org/mirrors.aliyun.com/g' /etc/apk/repositories && apk update && apk add curl

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有任何问题和建议，都可以向我提问讨论,大家一起进步，谢谢!

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