Gson简单过滤工具类封装

为手机app封装接口，需要把结果转换成json，这里用到了gson，但是有很多属性是不能对外暴露的，因此要过滤掉，gson自带的策略能够实现，但是代码一大坨

@Testpublic void testStrategy(){final Set<String> excludeAttr = Sets.newHashSet();//需要排除的属性excludeAttr.add("age");final Map<String,String> translateNameMap = Maps.newHashMap();//需要更改名称的属性translateNameMap.put("name", "employeeName");Gson gson = new GsonBuilder().serializeNulls().addSerializationExclusionStrategy(new ExclusionStrategy() {@Overridepublic boolean shouldSkipField(FieldAttributes attr) {return excludeAttr.contains(attr.getName()) ? true: false;}@Overridepublic boolean shouldSkipClass(Class<?> clazz) {return false;}}).setFieldNamingStrategy(new FieldNamingStrategy() {@Overridepublic String translateName(Field field) {return translateNameMap.get(field.getName()) == null ? field.getName() : translateNameMap.get(field.getName());}}).create();Employee employee = new Employee();employee.setId("1");employee.setName("dean");employee.setAge(32);employee.setEntryDate(new Date());String json = gson.toJson(employee);System.out.println(json);List<Employee> employeeList = Lists.newArrayList();employeeList.add(employee);String json1 = gson.toJson(employeeList);System.out.println(json1);}

重用性不够高，于是自己封装了一个简单的工具类

public class GsonSimplePreFilter {// 当includes的size > 0时，属性必须在includes中才会被序列化，excludes优先于includes，全局的excludes和includes优先于过滤类中的excludes和includesprivate final Set<String> includes = Sets.newHashSet();private final Set<String> excludes = Sets.newHashSet();private final Map<String, String> translateNames = Maps.newHashMap();private final List<FilterClass> filterClassList = Lists.newArrayList();private GsonBuilder gsonBuilder;public GsonSimplePreFilter() {gsonBuilder = CommonUtils.getDefaultGsonBuilder();}public GsonSimplePreFilter(GsonBuilder gsonBuilder) {this.gsonBuilder = gsonBuilder;}public Gson create() {final int includesCount = includes.size();final int excludesCount = excludes.size();return gsonBuilder.addSerializationExclusionStrategy(new ExclusionStrategy() {@Overridepublic boolean shouldSkipField(FieldAttributes attr) {if (excludesCount > 0&& excludes.contains(attr.getName())) {return true;} else {if (includesCount > 0&& !includes.contains(attr.getName())) {return true;}}for (FilterClass filterClass : filterClassList) {if (attr.getDeclaringClass().getName().equals(filterClass.getClazz().getName())) {if (filterClass.getExcludes().size() > 0&& filterClass.getExcludes().contains(attr.getName())) {return true;} else {if (filterClass.getIncludes().size() > 0&& !filterClass.getIncludes().contains(attr.getName())) {return true;}}}}return false;}@Overridepublic boolean shouldSkipClass(Class<?> clazz) {return false;}}).setFieldNamingStrategy(new FieldNamingStrategy() {@Overridepublic String translateName(Field field) {if (translateNames.get(field.getName()) != null) {return translateNames.get(field.getName());} else {for (FilterClass filterClass : filterClassList) {if (field.getDeclaringClass().getName().equals(filterClass.getClazz().getName())) {if (filterClass.getTranslateNames().get(field.getName()) != null) {return filterClass.getTranslateNames().get(field.getName());}}}}return field.getName();}}).create();}/** * 需要保留的属性 *  * @param attr * @return */public GsonSimplePreFilter setIncludes(String... attr) {includes.addAll(Arrays.asList(attr));return this;}/** * 需要排除的属性 *  * @param attr * @return */public GsonSimplePreFilter setExcludes(String... attr) {excludes.addAll(Arrays.asList(attr));return this;}/** * 转换属性名称 *  * @param old *            转换前 * @param now *            转换后 * @return */public GsonSimplePreFilter setTranslateNames(String old, String now) {translateNames.put(old, now);return this;}public Set<String> getIncludes() {return includes;}public Set<String> getExcludes() {return excludes;}public Map<String, String> getTranslateNames() {return translateNames;}public List<FilterClass> getFilterClassList() {return filterClassList;}public FilterClassBuidler createBuilder() {return new FilterClassBuidler(this);}/** * 静态内部类构造器 * */public static final class FilterClassBuidler {private GsonSimplePreFilter gsonFilter;private FilterClass filterClass;FilterClassBuidler(GsonSimplePreFilter instant) {gsonFilter = instant;}/** * 设置要进行过滤的类 * @param clazz * @return */public FilterClassBuidler setFilterClass(Class<?> clazz) {filterClass = new FilterClass();filterClass.setClazz(clazz);gsonFilter.getFilterClassList().add(filterClass);return this;}/** * 设置要过滤的类中需要被排除的属性 * @param attr * @return */public FilterClassBuidler setClassExcludes(String... attr) {filterClass.getExcludes().addAll(Arrays.asList(attr));return this;}/** * 设置要过滤的类中需要被包含的属性 * @param attr * @return */public FilterClassBuidler setClassIncludes(String... attr) {filterClass.getIncludes().addAll(Arrays.asList(attr));return this;}/** * 设置要过滤的类中需要被转换的属性 * @return */public FilterClassBuidler setClassTranslateNames(String old, String now) {filterClass.getTranslateNames().put(old, now);return this;}/** * 构造为GsonSimplePreFilter * @return */public GsonSimplePreFilter buildPreFilter() {return gsonFilter;}}public static final class FilterClass {Class<?> clazz;Set<String> includes = new HashSet<String>();Set<String> excludes = new HashSet<String>();Map<String, String> translateNames = new HashMap<String, String>();public Class<?> getClazz() {return clazz;}public void setClazz(Class<?> clazz) {this.clazz = clazz;}public Set<String> getIncludes() {return includes;}public void setIncludes(Set<String> includes) {this.includes = includes;}public Set<String> getExcludes() {return excludes;}public void setExcludes(Set<String> excludes) {this.excludes = excludes;}public Map<String, String> getTranslateNames() {return translateNames;}public void setTranslateNames(Map<String, String> translateNames) {this.translateNames = translateNames;}}public static void main(String[] args) {EduCourse c = new EduCourse();c.setId("1");c.setName("2");c.setRemark("3");c.setLessonId("zzzz");// 例子1只序列化name remark字段 并且把字段名称name改成namenameGson gson = new GsonSimplePreFilter().setIncludes("name", "remark").setTranslateNames("name", "namename").create();System.out.println(gson.toJson(c));// 例子2 不序列化"id", "remark"GsonBuilder buidler = new GsonBuilder();Gson gson1 = new GsonSimplePreFilter(buidler).setExcludes("id", "remark").setTranslateNames("name", "namename").create();System.out.println(gson1.toJson(c));EduStudent student = new EduStudent();student.setId("222");student.setName("3333");student.setAge(33);//例子3 多个对象，可以全局包含和排除，也可以对局部对象的包含和排除Map<String, Object> map = Maps.newHashMap();map.put("course", c);map.put("student", student);Gson gson2 = new GsonSimplePreFilter().setExcludes("id").setTranslateNames("name", "namename").createBuilder().setFilterClass(EduStudent.class).setClassExcludes("state").setClassTranslateNames("age", "age1111").setFilterClass(EduCourse.class).setClassExcludes("lessonsNum").setClassTranslateNames("goodsPrice", "goodsPrice2222").buildPreFilter().create();System.out.println(gson2.toJson(map));}}

可以支持平时大部分使用的场景，特殊情况肯定还是需要特殊处理