# 第01章 org.json
# 1.1 JSON-Java API
JSONObject原生put方法构建JSON
JSON官网 http://json.org/ JSON-java API： http://stleary.github.io/JSON-java/index.html
包的引入（gradle）：
// https://mvnrepository.com/artifact/org.json/json
compile group: 'org.json', name: 'json', version: '20180130'
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使用程序创建一个json对象如下：
package com.changan.org_json;
import org.json.JSONObject;
public class JSONObjectSample {
public static void main(String[] args) {
jsonObjectTest();
}
private static void jsonObjectTest() {
JSONObject wangxiaoer = new JSONObject();
Object nullObj = null;
wangxiaoer.put("name", "王小二");
wangxiaoer.put("age", 25.2);
wangxiaoer.put("birthday", "1990-08-23");
wangxiaoer.put("school", "蓝翔");
wangxiaoer.put("major", new String[]{"理发", "挖掘机"});
wangxiaoer.put("has_girlfriend", nullObj);
wangxiaoer.put("car", nullObj);
wangxiaoer.put("house", nullObj);
wangxiaoer.put("comment", "这是一个注释");
System.out.println(wangxiaoer.toString());
}
}
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输出结果：
# 1.2 使用Map构建JSON
JSONObject(java.util.Map<?,?> map) 使用Map构建一个JSONObject
package com.changan.org_json;
import org.json.JSONObject;
import java.util.HashMap;
import java.util.Map;
public class JSONObjectSample {
public static void main(String[] args) {
//jsonObjectTest();
createJsonByMap();
}
private static void jsonObjectTest() {
JSONObject wangxiaoer = new JSONObject();
Object nullObj = null;
wangxiaoer.put("name", "王小二");
wangxiaoer.put("age", 25.2);
wangxiaoer.put("birthday", "1990-08-23");
wangxiaoer.put("school", "蓝翔");
wangxiaoer.put("major", new String[]{"理发", "挖掘机"});
wangxiaoer.put("has_girlfriend", nullObj);
wangxiaoer.put("car", nullObj);
wangxiaoer.put("house", nullObj);
wangxiaoer.put("comment", "这是一个注释");
System.out.println(wangxiaoer.toString());
}
private static void createJsonByMap() {
Map<String, Object> wangxiaoer = new HashMap<>();
Object nullObj = null;
wangxiaoer.put("name", "王小二");
wangxiaoer.put("age", 25.2);
wangxiaoer.put("birthday", "1990-08-23");
wangxiaoer.put("school", "蓝翔");
wangxiaoer.put("major", new String[]{"理发", "挖掘机"});
wangxiaoer.put("has_girlfriend", nullObj);
wangxiaoer.put("car", nullObj);
wangxiaoer.put("house", nullObj);
wangxiaoer.put("comment", "这是一个注释");
System.out.println(new JSONObject(wangxiaoer).toString());
}
}
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# 1.3 使用JavaBean构建JSONObject
(实际开发中使用较多)
JSONObject(java.lang.Object bean) 使用对象的Bean属性的getter方法构建一个JSONObject Construct a JSONObject from an Object using bean getters. 如果不生成getter方法则输出为{}
package com.changan.org_json;
import org.json.JSONObject;
import java.util.HashMap;
import java.util.Map;
public class JSONObjectSample {
public static void main(String[] args) {
//jsonObjectTest();
//createJsonByMap();
createJsonByBean();
}
private static void jsonObjectTest() {
JSONObject wangxiaoer = new JSONObject();
Object nullObj = null;
wangxiaoer.put("name", "王小二");
wangxiaoer.put("age", 25.2);
wangxiaoer.put("birthday", "1990-08-23");
wangxiaoer.put("school", "蓝翔");
wangxiaoer.put("major", new String[]{"理发", "挖掘机"});
wangxiaoer.put("has_girlfriend", nullObj);
wangxiaoer.put("car", nullObj);
wangxiaoer.put("house", nullObj);
wangxiaoer.put("comment", "这是一个注释");
System.out.println(wangxiaoer.toString());
}
private static void createJsonByMap() {
Map<String, Object> wangxiaoer = new HashMap<>();
Object nullObj = null;
wangxiaoer.put("name", "王小二");
wangxiaoer.put("age", 25.2);
wangxiaoer.put("birthday", "1990-08-23");
wangxiaoer.put("school", "蓝翔");
wangxiaoer.put("major", new String[]{"理发", "挖掘机"});
wangxiaoer.put("has_girlfriend", nullObj);
wangxiaoer.put("car", nullObj);
wangxiaoer.put("house", nullObj);
wangxiaoer.put("comment", "这是一个注释");
System.out.println(new JSONObject(wangxiaoer).toString());
}
private static void createJsonByBean() {
Person wangxiaoer = new Person();
wangxiaoer.setName("王小二");
wangxiaoer.setAge(25.2);
wangxiaoer.setBirthday("1990-08-23");
wangxiaoer.setSchool("蓝翔");
wangxiaoer.setMajor(new String[]{"理发", "挖掘机"});
wangxiaoer.setHas_girfriend(false);
wangxiaoer.setCar(null);
wangxiaoer.setHouse(null);
wangxiaoer.setComment("这是一个注释");
System.out.println(new JSONObject(wangxiaoer));
}
}
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对象：
package com.changan.org_json;
public class Person {
private String name;
private String school;
private boolean has_girfriend;
private double age;
private Object car;
private Object house;
private String[] major;
private String comment;
private String birthday;
// getter & setter
}
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# 1.4 从文件中读取JSON（JSON解析）
JSONObject(java.lang.String source) Construct a JSONObject from a source JSON text string. 通过文本构建JSONObject 依赖jar包：commons-io 创建一个文件：wangxiaoer.json，如下
{
"birthday":"1990-08-23",
"has_girfriend":false,
"major":[
"理发",
"挖掘机"
],
"school":"蓝翔",
"name":"王小二",
"comment":"这是一个注释",
"age":25.2
}
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添加apache.common依赖
// https://mvnrepository.com/artifact/commons-io/commons-io
compile group: 'commons-io', name: 'commons-io', version: '2.6'
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代码：
package com.changan.org_json;
import org.apache.commons.io.FileUtils;
import org.json.JSONArray;
import org.json.JSONObject;
import java.io.File;
import java.io.IOException;
public class ReadJsonSample {
public static void main(String[] args) throws IOException {
File file = new File(ReadJsonSample.class.getResource("/wangxiaoer.json").getFile());
String content = FileUtils.readFileToString(file, "UTF-8");
JSONObject jsonObject = new JSONObject(content);
System.out.println("姓名 = " + jsonObject.getString("name"));
System.out.println("年龄 = " + jsonObject.getDouble("age"));
System.out.println("有女朋友吗？ = " + jsonObject.getBoolean("has_girlfriend"));
//获取数组使用JSONArray
JSONArray majorArray = jsonObject.getJSONArray("major");
for (int i = 0; i < majorArray.length(); i++) {
String major = (String)majorArray.get(i);
System.out.println("专业"+(i+1)+":"+major);
}
}
}
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# 1.5 从文件读取JSON判断null
boolean isNull(java.lang.String key) Determine if the value associated with(与什么关联) the key is null or if there is no value. 判断与该key关联的值是否是null，是则返回true，不是null则返回false
package com.changan.org_json;
import org.apache.commons.io.FileUtils;
import org.json.JSONArray;
import org.json.JSONObject;
import java.io.File;
import java.io.IOException;
public class ReadJsonSample {
public static void main(String[] args) throws IOException {
File file = new File(ReadJsonSample.class.getResource("/wangxiaoer.json").getFile());
String content = FileUtils.readFileToString(file, "UTF-8");
JSONObject jsonObject = new JSONObject(content);
if (!jsonObject.isNull("name")) {
System.out.println("姓名 = " + jsonObject.getString("name"));
}
if (!jsonObject.isNull("age")) {
System.out.println("年龄 = " + jsonObject.getDouble("age"));
}
if (!jsonObject.isNull("has_girlfriend")) {
System.out.println("有女朋友吗？ = " + jsonObject.getBoolean("has_girlfriend"));
}
//获取数组使用JSONArray
JSONArray majorArray = jsonObject.getJSONArray("major");
for (int i = 0; i < majorArray.length(); i++) {
String major = (String)majorArray.get(i);
System.out.println("专业"+(i+1)+":"+major);
}
}
}
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