Jackson的使用(json解析)

Jackson：高性能的JSON处理，处理json速度快。
Jackson可以轻松的将Java对象转换成json字符串和xml文档，同样也可以将json字符串、xml转换成Java对象。

代码如下:

package com.example.administrator.jsckson.ui;import android.os.Bundle;import android.support.annotation.Nullable;import android.support.v7.app.AppCompatActivity;import android.util.Log;import com.example.administrator.jsckson.R;import com.example.administrator.jsckson.entity.Name;import com.example.administrator.jsckson.entity.Student;import com.fasterxml.jackson.annotation.JsonInclude;import com.fasterxml.jackson.core.JsonGenerator;import com.fasterxml.jackson.core.JsonParser;import com.fasterxml.jackson.core.type.TypeReference;import com.fasterxml.jackson.databind.DeserializationFeature;import com.fasterxml.jackson.databind.ObjectMapper;import java.text.SimpleDateFormat;import java.util.ArrayList;import java.util.Date;import java.util.HashMap;import java.util.List;import java.util.Map;/** * Created on 2017/5/4. * Author:crs * Description:测试jackson */public class TestJacksonActivity extends AppCompatActivity {    private static final String TAG ="TestJacksonActivity" ;    private Student student1;    private ArrayList<Student> list;    private HashMap<String, Student> map;    @Override    protected void onCreate(@Nullable Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_test_jackson);        /**         * 1)JSON属于序列化与反序列化的内容         * 2)数据传输速度，数据解析速度         * 3)常用的json解析框架，以及一些配置         */        initData();        ObjectMapper mapper=getDefaultObjectMapper();        try {            //1)序列化对象 Object---->String            String s = mapper.writeValueAsString(student1);            Log.i(TAG,s);            //2)序列化集合 list---->String            String s1 = mapper.writeValueAsString(list);            Log.i(TAG,s1);            //3)序列化集合 map---->String            String s2 = mapper.writeValueAsString(map);            Log.i(TAG,s2);            //4)反序列化 json---->Object(这个应该是最常用的)            Student jsonToObject = mapper.readValue(s, Student.class);            Log.i(TAG,jsonToObject.toString());            //5)反序列化 json---->List            List<Student>  jsonToList = mapper.readValue(s1, new TypeReference<List<Student>>() {});            Log.i(TAG,jsonToList.toString());            //6)反序列化 json---->map            Map<String,Student> jsonToMap = mapper.readValue(s2, new TypeReference<Map<String,Student>>() {});            Log.i(TAG,jsonToMap.toString());        } catch (Exception e) {            e.printStackTrace();        }    }    private static ObjectMapper getDefaultObjectMapper() {        /**         * ObjectMapper是JSON操作的核心类，Jackson的所有JSON操作都是在ObjectMapper中实现。         * ObjectMapper有多个JSON序列化的方法，可以把JSON字符串保存File、OutputStream等不同的介质中。         * writeValueAsString(Object arg0)把arg0转成json序列，并把结果输出成字符串。         * JSON注解 Jackson提供了一系列注解，方便对JSON序列化和反序列化进行控制.         */        ObjectMapper mapper = new ObjectMapper();        //1)设置将对象转换成JSON字符串时候(序列化时)；序列化与反序列化。//如果对象的属性为null或者“”，此属性不在进行序列化        mapper.setSerializationInclusion(JsonInclude.Include.NON_EMPTY);        //JsonInclude.Include.NON_NULL;属性为NULL 不序列化        //JsonInclude.Include.ALWAYS ;默认        //2)设置有属性不能映射时不报错        mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);        mapper.configure(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT, true);        mapper.configure(JsonParser.Feature.ALLOW_UNQUOTED_CONTROL_CHARS, true);        //3)不能包含ASCII码        mapper.configure(JsonGenerator.Feature.ESCAPE_NON_ASCII, true);        //4)设置转换时的时间格式        mapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"));        return mapper;    }    private void initData() {        //准备数据，创建对象        Name name1 = new Name("陈诗音", "音");        Name name2 = new Name("陈诗乐", "乐");        Name name3 = new Name("陈随心", "心");        student1 = new Student(1,name1,"语文",new Date());        Student student2 = new Student(2,name2,"数学",new Date());        Student student3 = new Student(3,name3,"英语",new Date());        list = new ArrayList<>();        list.add(student1);        list.add(student2);        list.add(student3);        map = new HashMap<>();        map.put("1", student1);        map.put("2",student2);        map.put("3",student3);    }}

实体模型:

package com.example.administrator.jsckson.entity;import com.fasterxml.jackson.annotation.JsonFormat;import com.fasterxml.jackson.annotation.JsonIgnore;import com.fasterxml.jackson.annotation.JsonProperty;import java.util.Date;/** * Created on 2017/5/4. * Author:crs * Description:模型类student */public class Student {    @JsonIgnore //此注解用于属性上，作用是进行JSON操作时忽略该属性。    private int id;    @JsonProperty("firstName")//此注解用于属性上，作用是把该属性的名称序列化为另外一个名称，如把Name属性序列化为firstName    private Name name;//没有使用内部类    private String className;    @JsonFormat(pattern = "yyyy年MM月dd日") //格式化日期属性    private Date birthDay;        public Student(int id, Name name, String className, Date birthDay) {        this.id = id;        this.name = name;        this.className = className;        this.birthDay = birthDay;    }    public int getId() {        return id;    }    public void setId(int id) {        this.id = id;    }    public Name getName() {        return name;    }    public void setName(Name name) {        this.name = name;    }    public String getClassName() {        return className;    }    public void setClassName(String className) {        this.className = className;    }    public Date getBirthDay() {        return birthDay;    }    public void setBirthDay(Date birthDay) {        this.birthDay = birthDay;    }    @Override    public String toString() {        return "Student{" +                "id=" + id +                ", name=" + name +                ", className='" + className + '\'' +                ", birthDay=" + birthDay +                '}';    }}