基于json-lib.jar包Json实例程序 1.JSONObject to DynaBean String json = "{name=\"json\",bool:true,int:1,double:2.2}"; JSONObject jsonObject = JSONObject.fromObject(json); //抽象的写法:DynaBean bean = (DynaBean) JSONSerializer.toJava( jsonObject ); Object bean = JSONObject.toBean(jsonObject); //Object bean1 = JSONSerializer.toJava(jsonObject); assertEquals(jsonObject.get("name"), PropertyUtils.getProperty(bean, "name")); assertEquals(jsonObject.get("bool"), PropertyUtils.getProperty(bean, "bool")); assertEquals(jsonObject.get("int"), PropertyUtils.getProperty(bean, "int")); assertEquals(jsonObject.get("double"), PropertyUtils.getProperty(bean, "double")); 2.JSONObject to JavaBean String json = "{name:\"zhangsan\",age:25,hight:1.72,sex:true}"; JSONObject jsonObject = JSONObject.fromObject(json); UserBean bean = (UserBean) JSONObject.toBean(jsonObject, UserBean.class); System.out.println(jsonObject); 理论上,这样就可以了,但时,有异常Caused by: java.lang.NoSuchMethodException: com.json.Json$UserBean.<init>() 3.JSONArray to List String json = "[\"first\",\"second\"]"; JSONArray jsonArray = (JSONArray) JSONSerializer.toJSON(json); List output = (List) JSONSerializer.toJava(jsonArray); 4.JSONArray to array String json = "[\"first\",\"second\"]"; JSONArray jsonArray = (JSONArray) JSONSerializer.toJSON(json); JsonConfig jsonConfig = new JsonConfig(); jsonConfig.setArrayMode(JsonConfig.MODE_OBJECT_ARRAY); Object[] output = (Object[]) JSONSerializer.toJava(jsonArray, jsonConfig); Object[] expected = new Object[] { "first", "second" }; ArrayAssertions.assertEquals(expected, output); 5.JSON 字符串 专为 JavaBean(刘慧斌demo 演示需要的jar包在附件里) String str="[{\"id\":\"328\",\"mestype\":\"inbox\"},{\"id\":\"327\",\"mestype\":\"inbox\"},{\"id\":\"279\",\"mestype\":\"already\"},{\"id\":\"278\",\"mestype\":\"already\"},{\"id\":\"277\",\"mestype\":\"already\"},{\"id\":\"310\",\"mestype\":\"inbox\"},{\"id\":\"308\",\"mestype\":\"inbox\"},{\"id\":\"305\",\"mestype\":\"inbox\"},{\"id\":\"304\",\"mestype\":\"inbox\"},{\"id\":\"303\",\"mestype\":\"inbox\"}]"; JSONArray jsonArray=(JSONArray) JSONSerializer.toJSON(str); List list=(List)JSONSerializer.toJava(jsonArray); for (Object obj: list) { JSONObject jsonObject = JSONObject.fromObject(obj); MessageBean bean = (MessageBean) JSONObject.toBean(jsonObject, MessageBean.class); String id=bean.getId()+""; String type=bean.getMestype(); System.out.println(id+" "+type); } System.out.println(list.size());
http://blog.sina.com.cn/s/blog_9d0ce63d01012vmd.html JacksonDemo及使用方法
本文依据springside实例,演示Jackson的基本使用方式及大量的特殊Feature.一共13种使用方法。
public class JsonDemo { private static JsonMapper mapper = JsonMapper.buildNonDefaultMapper(); 1、序列化对象/集合到Json字符串. @Test public void toJson() throws Exception { //Bean TestBean bean = new TestBean("A"); String beanString = mapper.toJson(bean); System.out.println("Bean:" + beanString); assertEquals("{"name":"A"}", beanString); //Map Map<String, Object> map = Maps.newLinkedHashMap(); map.put("name", "A"); map.put("age", 2); String mapString = mapper.toJson(map); System.out.println("Map:" + mapString); assertEquals("{"name":"A","age":2}", mapString); //List<String> List<String> stringList = Lists.newArrayList("A", "B", "C"); String listString = mapper.toJson(stringList); System.out.println("String List:" + listString); assertEquals("["A","B","C"]", listString); //List<Bean> List<TestBean> beanList = Lists.newArrayList(new TestBean("A"), new TestBean("B")); String beanListString = mapper.toJson(beanList); System.out.println("Bean List:" + beanListString); assertEquals("[{"name":"A"},{"name":"B"}]", beanListString); //Bean[] TestBean[] beanArray = new TestBean[] { new TestBean("A"), new TestBean("B") }; String beanArrayString = mapper.toJson(beanArray); System.out.println("Array List:" + beanArrayString); assertEquals("[{"name":"A"},{"name":"B"}]", beanArrayString); } 2、从Json字符串反序列化对象/集合. @Test public void fromJson() throws Exception { //Bean String beanString = "{"name":"A"}"; TestBean bean = mapper.fromJson(beanString, TestBean.class); System.out.println("Bean:" + bean); //Map String mapString = "{"name":"A","age":2}"; Map<String, Object> map = mapper.fromJson(mapString, HashMap.class); System.out.println("Map:"); for (Entry<String, Object> entry : map.entrySet()) { System.out.println(entry.getKey() + " " + entry.getValue()); } //List<String> String listString = "["A","B","C"]"; List<String> stringList = mapper.fromJson(listString, List.class); System.out.println("String List:"); for (String element : stringList) { System.out.println(element); } //List<Bean> String beanListString = "[{"name":"A"},{"name":"B"}]"; JavaType beanListType = mapper.constructParametricType(List.class, TestBean.class); List<TestBean> beanList = mapper.fromJson(beanListString, beanListType); System.out.println("Bean List:"); for (TestBean element : beanList) { System.out.println(element); } } 3、 测试三种不同的Binder. @Test public void threeTypeBinders() { TestBean bean = new TestBean("A"); //打印全部属性 JsonMapper normalMapper = JsonMapper.buildNormalMapper(); assertEquals("{"nullValue":null,"name":"A","defaultValue":"hello"}", normalMapper.toJson(bean)); //不打印nullValue属性 JsonMapper nonNullMapper = JsonMapper.buildNonNullMapper(); assertEquals("{"name":"A","defaultValue":"hello"}", nonNullMapper.toJson(bean)); //不打印默认值未改变的nullValue与defaultValue属性 JsonMapper nonDefaultMaper = JsonMapper.buildNonDefaultMapper(); assertEquals("{"name":"A"}", nonDefaultMaper.toJson(bean)); } 4、测试传入空对象,空字符串,Empty的集合,"null"字符串的结果. @Test public void nullAndEmpty() { // toJson测试 // //Null Bean TestBean nullBean = null; String nullBeanString = mapper.toJson(nullBean); assertEquals("null", nullBeanString); //Empty List List<String> emptyList = Lists.newArrayList(); String emptyListString = mapper.toJson(emptyList); assertEquals("[]", emptyListString); // fromJson测试 // //Null String for Bean TestBean nullBeanResult = mapper.fromJson(null, TestBean.class); assertNull(nullBeanResult); nullBeanResult = mapper.fromJson("null", TestBean.class); assertNull(nullBeanResult); //Null/Empty String for List List nullListResult = mapper.fromJson(null, List.class); assertNull(nullListResult); nullListResult = mapper.fromJson("null", List.class); assertNull(nullListResult); nullListResult = mapper.fromJson("[]", List.class); assertEquals(0, nullListResult.size()); } 5、测试对枚举的序列化,可以选择用一个int字段而不是以Name来序列化,以减少少长度. @Test public void enumData() { //默認使用enum.name() assertEquals(""One"", mapper.toJson(TestEnum.One)); assertEquals(TestEnum.One, mapper.fromJson(""One"", TestEnum.class)); //使用enum.toString() //注意,index會通過toString序列成字符串而不是int,否則又和順序號混淆. //注意配置必須在所有讀寫動作之前調用. JsonMapper newMapper = JsonMapper.buildNormalMapper(); newMapper.setEnumUseToString(true); assertEquals(""1"", newMapper.toJson(TestEnum.One)); assertEquals(TestEnum.One, newMapper.fromJson(""1"", TestEnum.class)); } 枚举的演示Bean. public static enum TestEnum { One(1), Two(2), Three(3); private int index; TestEnum(int index) { this.index = index; } @Override public String toString() { return new Integer(index).toString(); } } 6、测试对日期的序列化. @Test public void dateData() { DateTime jodaDate = new DateTime(); //日期默认以Timestamp方式存储 Date date = new Date(jodaDate.getMillis()); String tsString = String.valueOf(jodaDate.getMillis()); assertEquals(tsString, mapper.toJson(date)); assertEquals(date, mapper.fromJson(tsString, Date.class)); } 7、 JSON字符串里只含有Bean中部分的属性,更新一个已存在Bean,只覆蓋部分的属性. @Test public void updateBean() { String jsonString = "{"name":"A"}"; TestBean bean = new TestBean(); bean.setDefaultValue("Foobar"); bean = mapper.update(bean, jsonString); assertEquals("A", bean.getName()); assertEquals("Foobar", bean.getDefaultValue()); } 8、测试父子POJO间的循环引用. @Test public void parentChildBean() { //初始化对象关系,parent的Childs里含有 child1,child2, child1/child2的parent均指向parent. ParentChildBean parent = new ParentChildBean("parent"); ParentChildBean child1 = new ParentChildBean("child1"); child1.setParent(parent); parent.getChilds().add(child1); ParentChildBean child2 = new ParentChildBean("child2"); child2.setParent(parent); parent.getChilds().add(child2); String jsonString = "{"childs":[{"name":"child1"},{"name":"child2"}],"name":"parent"}"; //打印parent的json输出,json字符串裡childs中的child1/child2都不包含到parent的屬性 assertEquals(jsonString, mapper.toJson(parent)); //注意此時如果單獨打印child1,也不會打印parent,信息將丟失。 assertEquals("{"name":"child1"}", mapper.toJson(child1)); //反向序列化时,Json已很聪明的把parent填入child1/child2中. ParentChildBean parentResult = mapper.fromJson(jsonString, ParentChildBean.class); assertEquals("parent", parentResult.getChilds().get(0).getParent().getName()); } 父子POJO父子POJO的演示Bean,@JsonBackReference 与 @JsonManagedReference 是关键. public static class ParentChildBean { private String name; private ParentChildBean parent; public List<ParentChildBean> childs = Lists.newArrayList(); public ParentChildBean() { } public ParentChildBean(String name) { this.name = name; } public String getName() { return name; } public void setName(String name) { this.name = name; } //注意getter與setter都要添加annotation @JsonBackReference public ParentChildBean getParent() { return parent; } @JsonBackReference public void setParent(ParentChildBean parent) { this.parent = parent; } @JsonManagedReference public List<ParentChildBean> getChilds() { return childs; } @JsonManagedReference public void setChilds(List<ParentChildBean> childs) { this.childs = childs; } } 9、測試可擴展Bean,會自動的把確定的屬性放入固定的成員變量, 其他屬性放到一个类型为Map的成员变量裡,能很好的支持Bean版本升级时固定属性的变动. @Test public void extensibleBean() { //一个没有区分是变量还是Map的普通JSON字符串. String jsonString = "{"name" : "Foobar","age" : 37,"occupation" : "coder man"}"; ExtensibleBean extensibleBean = mapper.fromJson(jsonString, ExtensibleBean.class); assertEquals("Foobar", extensibleBean.getName()); assertEquals(null, extensibleBean.getProperties().get("name")); assertEquals("coder man", extensibleBean.getProperties().get("occupation")); } 演示用的可擴展Bean.@JsonAnySetter与@JsonAnyGetter是关键. public static class ExtensibleBean { private String name; // we always have name private HashMap<String, String> properties = Maps.newHashMap(); public ExtensibleBean() { } @JsonAnySetter public void add(String key, String value) { properties.put(key, value); } @JsonAnyGetter public Map<String, String> getProperties() { return properties; } public String getName() { return name; } public void setName(String name) { this.name = name; } } 10、測試序列化Bean时使用不同的View序列化不同的属性组, 及@JsonIgnore標註的屬性. @Test public void viewBean() throws JsonGenerationException, JsonMappingException, IOException { ViewBean viewBean = new ViewBean(); viewBean.setName("Foo"); viewBean.setAge(16); viewBean.setOtherValue("others"); viewBean.setIgnoreValue("ignored"); ObjectWriter publicWriter = mapper.getMapper().writerWithView(Views.Public.class); assertEquals("{"otherValue":"others","name":"Foo"}", publicWriter.writeValueAsString(viewBean)); ObjectWriter internalWriter = mapper.getMapper().writerWithView(Views.Internal.class); assertEquals("{"age":16,"otherValue":"others"}", internalWriter.writeValueAsString(viewBean)); //設置默認是否顯示沒有用@Json定義的屬性 JsonMapper newMapper = JsonMapper.buildNormalMapper(); newMapper.getMapper().configure(SerializationConfig.Feature.DEFAULT_VIEW_INCLUSION, false); publicWriter = newMapper.getMapper().writerWithView(Views.Public.class); assertEquals("{"name":"Foo"}", publicWriter.writeValueAsString(viewBean)); } public static class Views { static class Public { } static class Internal { } } 演示序列化不同View不同属性的Bean. public static class ViewBean { private String name; private int age; private String otherValue; private String ignoreValue; @JsonView(Views.Public.class) public String getName() { return name; } public void setName(String name) { this.name = name; } @JsonView(Views.Internal.class) public int getAge() { return age; } public void setAge(int age) { this.age = age; } public String getOtherValue() { return otherValue; } public void setOtherValue(String otherValue) { this.otherValue = otherValue; } @JsonIgnore public String getIgnoreValue() { return ignoreValue; } public void setIgnoreValue(String ignoreValue) { this.ignoreValue = ignoreValue; } } 11、 测试自定义转换器 @Test public void customConverter() { JsonMapper newMapper = JsonMapper.buildNonNullMapper(); SimpleModule testModule = new SimpleModule("MyModule", new Version(1, 0, 0, null)); testModule.addSerializer(new MoneySerializer()); // assuming serializer declares correct class to bind to testModule.addDeserializer(Money.class, new MoneyDeserializer()); newMapper.getMapper().registerModule(testModule); Money money = new Money(1.2); String jsonString = newMapper.toJson(money); assertEquals(""1.2"", jsonString); Money resultMoney = newMapper.fromJson(jsonString, Money.class); assertEquals(new Double(1.2), resultMoney.value); } public class MoneySerializer extends SerializerBase<Money> { public MoneySerializer() { super(Money.class); } public void serialize(Money value, JsonGenerator jgen, SerializerProvider provider) throws IOException, JsonProcessingException { jgen.writeString(value.toString()); } } public class MoneyDeserializer extends StdDeserializer<Money> { public MoneyDeserializer() { super(Money.class); } @Override public Money deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException, JsonProcessingException { return Money.valueOf(jp.getText()); } } public static class Money { private Double value; public Money(Double value) { this.value = value; } public static Money valueOf(String value) { Double srcValue = Double.valueOf(value); return new Money(srcValue); } public String toString() { return value.toString(); } } 12、测试修改属性名策略 @Test public void customPropertyNameing() throws JsonMappingException { TestBean bean = new TestBean("foo"); bean.setDefaultValue("bar"); JsonMapper newMapper = JsonMapper.buildNonNullMapper(); newMapper.getMapper().setPropertyNamingStrategy(new LowerCaseNaming()); String jsonpString = newMapper.toJson(bean); assertEquals("{"name":"foo","defaultvalue":"bar"}", jsonpString); } public static class LowerCaseNaming extends PropertyNamingStrategy { @Override public String nameForGetterMethod(MapperConfig<?> config, AnnotatedMethod method, String defaultName) { return defaultName.toLowerCase(); } } 13、 測試輸出jsonp格式內容. @Test public void jsonp() { TestBean bean = new TestBean("foo"); String jsonpString = mapper.toJsonP("callback", bean); assertEquals("callback({"name":"foo"})", jsonpString); } 演示Bean, 主要演示不同風格的Mapper對Null值,初始化後沒改變過的屬性值的處理. public static class TestBean { private String name; private String defaultValue = "hello"; //默认值没被修改过的属性,可能会不序列化 private String nullValue = null; //空值的据行,可能会不序列化 public TestBean() { } public TestBean(String name) { this.name = name; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getDefaultValue() { return defaultValue; } public void setDefaultValue(String defaultValue) { this.defaultValue = defaultValue; } public String getNullValue() { return nullValue; } public void setNullValue(String nullValue) { this.nullValue = nullValue; } @Override public String toString() { return "TestBean [defaultValue=" + defaultValue + ", name=" + name + ", nullValue=" + nullValue + "]"; } } }