下载地址:http://maven.apache.org/download.cgi
image-20200718084505519
打开./apache-maven-3.6.3/conf/settings.xml
<mirrors>
<!-- mirror
| Specifies a repository mirror site to use instead of a given repository. The repository that
| this mirror serves has an ID that matches the mirrorOf element of this mirror. IDs are used
| for inheritance and direct lookup purposes, and must be unique across the set of mirrors.
|
-->
<mirror>
<id>nexus-aliyun</id>
<mirrorOf>*</mirrorOf>
<name>Nexus aliyun</name>
<url>https://maven.aliyun.com/repository/central</url>
</mirror>
</mirrors>
<localRepository>/Users/zhongxin/maven_download</localRepository>
将解压后的文件夹移动到/usr/local/apache-maven-3.6.3
$ vi ~/.bash_profile
进入文件后添加下面两行
export MAVEN_HOME=/usr/local/apache-maven-3.6.3
export PATH=$PATH:$MAVEN_HOME/bin
添加后保存
$ source ~/.bash_profile
测试
IDEA中配置
1
2
项目结构
新建文件夹
第三方包仓库https://mvnrepository.com/
以解析json的第三方库fastjson
为例
mvnrepository
搜索想要使用的第三方包<!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.72</version>
</dependency>
第三方包
<?xml version="1.0" encoding="UTF-8"?>
<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>org.example</groupId>
<artifactId>learn_java_maven</artifactId>
<version>1.0-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>fastjson</artifactId>
<version>1.2.72</version>
</dependency>
</dependencies>
</project>
fastjson工具类,静态方法 静态方法不需要创建对象,直接用 类名点 调用
import com.alibaba.fastjson.JSONObject;
{"name": "张三","age": 18,"source": 100}
package com.zhongxin.json;
public class Student {
private String name;
private int age;
private int score;
public Student(String name, int age, int score) {
this.name = name;
this.age = age;
this.score = score;
}
public Student() {
}
@Override
public String toString() {
return "Student{" +
"name='" + name + '\'' +
", age=" + age +
", score=" + score +
'}';
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public int getScore() {
return score;
}
public void setScore(int score) {
this.score = score;
}
}
package com.zhongxin.json;
import com.alibaba.fastjson.JSONObject;
public class Json {
public static void main(String[] args) {
String json = "{\"name\": \"张三\",\"age\": 18,\"source\": 100}";
Student s = JSONObject.parseObject(json, Student.class);
System.out.println(s);
}
}
警告提示
在pom.xml
中添加如下内容:
<properties>
<maven.compiler.target>1.8</maven.compiler.target>
<maven.compiler.source>1.8</maven.compiler.source>
<!-- 文件拷贝时的编码 -->
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<!-- 编译时的编码 -->
<maven.compiler.encoding>UTF-8</maven.compiler.encoding>
<aspectj.version>1.9.2</aspectj.version>
</properties>
不再提示警告
Student s2 = new Student("李四", 20, 90);
String json2 = JSONObject.toJSONString(s2);
System.out.println(json2);
输出{"age":20,"name":"李四","score":90}
Map<String, Object> map = JSONObject.parseObject(json, Map.class);
System.out.println(map);
输出{name=张三, source=100, age=18}
String json3 = JSONObject.toJSONString(map);
System.out.println(json3);
输出{"name":"张三","source":100,"age":18}
待转化:[{"name": "张三","age": 18},{"name": "李四","age": 16}]
定义Teacher
类
package com.zhongxin.json;
public class Teacher {
private String name;
private int age;
public Teacher() {
}
public Teacher(String name, int age) {
this.name = name;
this.age = age;
}
public String getName() {
return name;
}
public int getAge() {
return age;
}
@Override
public String toString() {
return "Teacher{" +
"name='" + name + '\'' +
", age=" + age +
'}';
}
public void setAge(int age) {
this.age = age;
}
public void setName(String name) {
this.name = name;
}
}
转化
package com.zhongxin.json;
import com.alibaba.fastjson.JSONObject;
import java.util.List;
public class Json2 {
public static void main(String[] args) {
String json = "[{\"name\": \"张三\",\"age\": 18},{\"name\": \"李四\",\"age\": 16}]";
List<Teacher> list = JSONObject.parseArray(json, Teacher.class);
for (Teacher t : list) {
System.out.println(t);
}
}
}
输出内容:
Teacher{name='张三', age=18} Teacher{name='李四', age=16}
使用Properties一般不使用Map接口的方法 Properties没有泛型,默认String
先要修改文件编码
修改编码
新建一个config.properties
文件../learn_java_maven/src/test/resources/config.properties
package com.zhongxin.properties;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Properties;
public class PropDemo {
public static void main(String[] args) throws IOException {
Properties prop = new Properties();
prop.setProperty("USERNAME", "张三");
prop.setProperty("PASSWORD", "123456");
System.out.println(prop.getProperty("USERNAME"));
System.out.println(prop.getProperty("PASSWORD"));
FileOutputStream fos = new FileOutputStream("src/test/resources/config.properties");
prop.save(fos, "注释");
fos.close();
}
}
查看config.properties
文件
#注释
#Sat Jul 18 10:05:03 CST 2020
USERNAME=张三
PASSWORD=123456
FileInputStream fis = new FileInputStream("src/test/resources/config.properties");
prop.load(fis);
System.out.println(prop);
输出:{USERNAME=张三, PASSWORD=123456}
往外抛出异常
可以进行异常捕获
try{
// 可能异常的代码
}catch(Exception e){
// 捕获异常,出现异常的解决方案
}finally{
// 释放资源
// 无论是否异常,一定会执行的代码
}