Google Gson 字段过滤：自定义过滤规则

本文内容大多基于官方文档和网上前辈经验总结，经过个人实践加以整理积累，仅供参考。

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Google Gson 支持自定义规则过滤字段，使用 GsonBuilder 类的 addSerializationExclusionStrategy 方法处理序列化过程中的字段过滤，使用 addDeserializationExclusionStrategy 方法处理反序列化过程中的字段过滤。这两个方法都接收 com.google.gson.ExclusionStrategy 接口类型参数

示例

1 addSerializationExclusionStrategy

(1) 基于 @Expose 注解过滤

POJO 类

class GsonObject {    public String field1 = "FIELD_1";    @Expose(serialize = true, deserialize = false)    public String field2 = "FIELD_2";    @Expose(serialize = false, deserialize = true)    public String field3 = "FIELD_3";    public String field4 = "FIELD_4";    @Override    public String toString() {        return "GsonObject [field1=" + field1 + ", field2=" + field2 + ", field3=" + field3 + ", field4=" + field4                + "]";    }}

测试代码：

@Testpublic void test() throws IOException {    Gson gson = new GsonBuilder()        .addSerializationExclusionStrategy(new ExclusionStrategy() {            @Override            public boolean shouldSkipField(FieldAttributes arg0) {                Expose expose = arg0.getAnnotation(Expose.class);                if (expose != null && expose.deserialize() == false) {                    return true;                }                return false;            }            @Override            public boolean shouldSkipClass(Class<?> arg0) {                return false;            }        }).create();    System.out.println(gson.toJson(new GsonObject()));}

运行结果：

(2) 基于字段名过滤

测试代码：

@Testpublic void test() throws IOException {    Gson gson = new GsonBuilder()        .addSerializationExclusionStrategy(new ExclusionStrategy() {            @Override            public boolean shouldSkipField(FieldAttributes arg0) {                if (arg0.getName().equals("field4")) {                    return true;                }                return false;            }            @Override            public boolean shouldSkipClass(Class<?> arg0) {                return false;            }        }).create();    System.out.println(gson.toJson(new GsonObject()));}

运行结果：

(3) 基于字段类型过滤

POJO 类

class GsonObject {    public String field1 = "FIELD_1";    public String field2 = "FIELD_2";    public String field3 = "FIELD_3";    public String field4 = "FIELD_4";    public int field5 = 5;    public double field6 = 6.0;    public boolean field7 = false;    @Override    public String toString() {        return "GsonObject [field1=" + field1 + ", field2=" + field2 + ", field3=" + field3 + ", field4=" + field4            + ", field5=" + field5 + ", field6=" + field6 + ", field7=" + field7 + "]";    }}

测试代码：

@Testpublic void test() throws IOException {    Gson gson = new GsonBuilder()        .setVersion(1)        .addSerializationExclusionStrategy(new ExclusionStrategy() {            @Override            public boolean shouldSkipField(FieldAttributes arg0) {                return false;            }            @Override            public boolean shouldSkipClass(Class<?> arg0) {                return (arg0 == double.class || arg0 == Double.class);            }        }).create();    System.out.println(gson.toJson(new GsonObject()));}

运行结果：

2 addDeserializationExclusionStrategy

(1) 基于 @Expose 注解过滤

POJO 类

class GsonObject {    private String field1;    @Expose(serialize = true, deserialize = false)    private String field2;    @Expose(serialize = false, deserialize = true)    private String field3;    private String field4;    public String getField1() {        return field1;    }    public void setField1(String field1) {        this.field1 = field1;    }    public String getField2() {        return field2;    }    public void setField2(String field2) {        this.field2 = field2;    }    public String getField3() {        return field3;    }    public void setField3(String field3) {        this.field3 = field3;    }    public String getField4() {        return field4;    }    public void setField4(String field4) {        this.field4 = field4;    }    @Override    public String toString() {        return "GsonObject [field1=" + field1 + ", field2=" + field2 + ", field3=" + field3 + ", field4=" + field4                + "]";    }}

测试代码：

@Testpublic void test() throws IOException {    Gson gson = new GsonBuilder()        .addDeserializationExclusionStrategy(new ExclusionStrategy() {            @Override            public boolean shouldSkipField(FieldAttributes arg0) {                Expose expose = arg0.getAnnotation(Expose.class);                if (expose != null && expose.deserialize() == true) {                    return true;                }                return false;            }            @Override            public boolean shouldSkipClass(Class<?> arg0) {                return false;            }        }).create();    String gsonStr = "{\"field1\":\"FIELD_A\","         + "\"field2\":\"FIELD_B\","         + "\"field3\":\"FIELD_C\","         + "\"field4\":\"FIELD_D\"}";    System.out.println(gson.fromJson(gsonStr, GsonObject.class));}

运行结果：

(2) 基于字段名过滤

测试代码：

@Testpublic void test() throws IOException {    Gson gson = new GsonBuilder()        .addDeserializationExclusionStrategy(new ExclusionStrategy() {            @Override            public boolean shouldSkipField(FieldAttributes arg0) {                if (arg0.getName().equals("field4")) {                    return true;                }                return false;            }            @Override            public boolean shouldSkipClass(Class<?> arg0) {                return false;            }        }).create();    String gsonStr = "{\"field1\":\"FIELD_A\","         + "\"field2\":\"FIELD_B\","         + "\"field3\":\"FIELD_C\","         + "\"field4\":\"FIELD_D\"}";    System.out.println(gson.fromJson(gsonStr, GsonObject.class));}

运行结果：

(3) 基于字段类型过滤

POJO 类

class GsonObject {    private String field1;    private String field2;    private String field3;    private String field4;    private int field5;    private double field6;    private boolean field7;    public String getField1() {        return field1;    }    public void setField1(String field1) {        this.field1 = field1;    }    public String getField2() {        return field2;    }    public void setField2(String field2) {        this.field2 = field2;    }    public String getField3() {        return field3;    }    public void setField3(String field3) {        this.field3 = field3;    }    public String getField4() {        return field4;    }    public void setField4(String field4) {        this.field4 = field4;    }    public int getField5() {        return field5;    }    public void setField5(int field5) {        this.field5 = field5;    }    public double getField6() {        return field6;    }    public void setField6(double field6) {        this.field6 = field6;    }    public boolean isField7() {        return field7;    }    public void setField7(boolean field7) {        this.field7 = field7;    }    @Override    public String toString() {        return "GsonObject [field1=" + field1 + ", field2=" + field2 + ", field3=" + field3 + ", field4=" + field4            + ", field5=" + field5 + ", field6=" + field6 + ", field7=" + field7 + "]";    }}

测试代码：

@Testpublic void test() throws IOException {    Gson gson = new GsonBuilder()        .setVersion(1)        .addDeserializationExclusionStrategy(new ExclusionStrategy() {            @Override            public boolean shouldSkipField(FieldAttributes arg0) {                return false;            }            @Override            public boolean shouldSkipClass(Class<?> arg0) {                return (arg0 == double.class || arg0 == Double.class);            }        }).create();    String gsonStr = "{\"field1\":\"FIELD_A\","         + "\"field2\":\"FIELD_B\","         + "\"field3\":\"FIELD_C\","         + "\"field4\":\"FIELD_D\","         + "\"field5\":55,"         + "\"field6\":99.99,"         + "\"field7\":true}";    System.out.println(gson.fromJson(gsonStr, GsonObject.class));}

运行结果：