上次说的加载jar包,有几个问题没有解决:
1、如果项目包含了其他的jar包如何解决?
2、如何规范上传的jar包的类和方法?
下面就解决一下上面两个问题
一、首先编写被调用的类,这次使用maven工程,并且载入了第三方jar包,阿里巴巴的fastjson包
package com.qunar.hello.hello; import java.util.HashMap; import com.alibaba.fastjson.JSON; public class HelloWorld extends Thread{ public void run(){ HashMap<String, String> m = new HashMap(); m.put("name", "liqiu"); System.out.println(JSON.toJSONString(m)); } }
二、打一个胖包,修改pom.xml,添加build
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.qunar.hello</groupId> <artifactId>hello</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>hello</name> <url>http://maven.apache.org</url> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8.1</version> <scope>test</scope> </dependency> <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.1.26</version> </dependency> </dependencies> <build> <plugins> <plugin> <artifactId>maven-assembly-plugin</artifactId> <configuration> <descriptorRefs> <descriptorRef>jar-with-dependencies</descriptorRef> </descriptorRefs> </configuration> </plugin> </plugins> </build> </project>
三、在命令行执行:mvn assembly:assembly
这时候你会发现在target目录出现一个jar:hello-0.0.1-SNAPSHOT-jar-with-dependencies.jar
四、调用这个胖jar包
package com.qunar.studyspring.javajar; import java.net.URL; import java.net.URLClassLoader; import java.lang.reflect.Method; public class JavaJar { public void doJar() { try { URL url = new URL("file:/Users/liqiu/Documents/workspace/hello/target/hello-0.0.1-SNAPSHOT-jar-with-dependencies.jar"); // 这里需要重点看URLClassLoader用法, URLClassLoader loader = new URLClassLoader(new URL[] { url }); // URL跟我们日常见到的格式用法不太一样 Class c = loader.loadClass("com.qunar.hello.hello.HelloWorld"); // 在上面找到并加载jar包后,可以通过此 Thread myObject = (Thread) c.newInstance(); // 函数加载某个类,并使用 newInstance myObject.run(); } catch (Exception ex) { System.out.println(ex); } } }
五、编写测试类
package com.qunar.studyspring; import org.junit.Test; import com.qunar.studyspring.javajar.JavaJar; public class JarTest { @Test public void sayHello(){ JavaJar javajar = new JavaJar(); javajar.doJar(); } }
六、运行的结果是:
{"name":"liqiu"}
时间: 2024-10-06 01:48:39