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cloud/dahua/src/main/java/com/example/dahua/utils/JsonUtils.java
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| 1 | +package com.example.dahua.utils; | ||
| 2 | + | ||
| 3 | +import com.fasterxml.jackson.annotation.JsonInclude.Include; | ||
| 4 | +import com.fasterxml.jackson.core.type.TypeReference; | ||
| 5 | +import com.fasterxml.jackson.databind.DeserializationFeature; | ||
| 6 | +import com.fasterxml.jackson.databind.JavaType; | ||
| 7 | +import com.fasterxml.jackson.databind.ObjectMapper; | ||
| 8 | +import org.apache.commons.lang.StringUtils; | ||
| 9 | +import org.slf4j.Logger; | ||
| 10 | +import org.slf4j.LoggerFactory; | ||
| 11 | + | ||
| 12 | +import java.io.IOException; | ||
| 13 | +import java.util.Map; | ||
| 14 | + | ||
| 15 | +/** | ||
| 16 | + * 类JsonMapper.java的实现描述：简单封装Jackson，实现JSON String<->Java Object的Mapper. | ||
| 17 | + * | ||
| 18 | + * <p> 封装不同的输出风格, 使用不同的builder函数创建实例. </p> | ||
| 19 | + * | ||
| 20 | + * @author xuquan | ||
| 21 | + */ | ||
| 22 | +public class JsonUtils { | ||
| 23 | + | ||
| 24 | + private static final Logger LOG = LoggerFactory.getLogger(JsonUtils.class); | ||
| 25 | + | ||
| 26 | + private ObjectMapper mapper; | ||
| 27 | + | ||
| 28 | + public JsonUtils(){ | ||
| 29 | + this(null); | ||
| 30 | + } | ||
| 31 | + | ||
| 32 | + public JsonUtils(Include include) { | ||
| 33 | + mapper = new ObjectMapper(); | ||
| 34 | + // 设置输出时包含属性的风格 | ||
| 35 | + if (include != null) { | ||
| 36 | + mapper.setSerializationInclusion(include); | ||
| 37 | + } | ||
| 38 | + // 设置输入时忽略在JSON字符串中存在但Java对象实际没有的属性 | ||
| 39 | + mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES); | ||
| 40 | + } | ||
| 41 | + | ||
| 42 | + /** | ||
| 43 | + * 创建只输出非Null且非Empty(如List.isEmpty)的属性到Json字符串的Mapper,建议在外部接口中使用. | ||
| 44 | + */ | ||
| 45 | + public static JsonUtils nonEmptyMapper() { | ||
| 46 | + return new JsonUtils(Include.NON_EMPTY); | ||
| 47 | + } | ||
| 48 | + | ||
| 49 | + /** | ||
| 50 | + * 创建只输出初始值被改变的属性到Json字符串的Mapper, 最节约的存储方式，建议在内部接口中使用。 | ||
| 51 | + */ | ||
| 52 | + public static JsonUtils nonDefaultMapper() { | ||
| 53 | + return new JsonUtils(Include.NON_DEFAULT); | ||
| 54 | + } | ||
| 55 | + | ||
| 56 | + /** | ||
| 57 | + * Object可以是POJO，也可以是Collection或数组。 | ||
| 58 | + * 如果对象为Null, 返回"null". | ||
| 59 | + * 如果集合为空集合, 返回"[]". | ||
| 60 | + */ | ||
| 61 | + public String toJson(Object object) { | ||
| 62 | + | ||
| 63 | + try { | ||
| 64 | + return mapper.writeValueAsString(object); | ||
| 65 | + } catch (IOException e) { | ||
| 66 | + LOG.warn(String.format("序列化成 JSON 字符串发生错误:%s", object), e); | ||
| 67 | + return null; | ||
| 68 | + } | ||
| 69 | + } | ||
| 70 | + | ||
| 71 | + /** | ||
| 72 | + * 反序列化POJO或简单Collection如List<String>. | ||
| 73 | + * | ||
| 74 | + * 如果JSON字符串为Null或"null"字符串, 返回Null. | ||
| 75 | + * 如果JSON字符串为"[]", 返回空集合. | ||
| 76 | + * | ||
| 77 | + * 如需反序列化复杂Collection如List<MyBean>, 请使用fromJson(String, JavaType) | ||
| 78 | + * | ||
| 79 | + * @see #fromJson(String, JavaType) | ||
| 80 | + */ | ||
| 81 | + public <T> T fromJson(String jsonString, Class<T> clazz) { | ||
| 82 | + if (StringUtils.isEmpty(jsonString)) { | ||
| 83 | + return null; | ||
| 84 | + } | ||
| 85 | + | ||
| 86 | + try { | ||
| 87 | + return mapper.readValue(jsonString, clazz); | ||
| 88 | + } catch (IOException e) { | ||
| 89 | + LOG.error(String.format("解析 JSON 字符串发生错误:%s", jsonString), e); | ||
| 90 | + return null; | ||
| 91 | + } | ||
| 92 | + } | ||
| 93 | + | ||
| 94 | + /** | ||
| 95 | + * 反序列化泛型对象 | ||
| 96 | + * @param <T> | ||
| 97 | + * @param jsonString | ||
| 98 | + * @param typeReference | ||
| 99 | + * @return | ||
| 100 | + */ | ||
| 101 | + public <T> T fromJson(String jsonString, TypeReference<T> typeReference) { | ||
| 102 | + if (StringUtils.isEmpty(jsonString)) { | ||
| 103 | + return null; | ||
| 104 | + } | ||
| 105 | + | ||
| 106 | + try { | ||
| 107 | + return mapper.readValue(jsonString, typeReference); | ||
| 108 | + } catch (IOException e) { | ||
| 109 | + LOG.error(String.format("解析 JSON 字符串发生错误:%s", jsonString), e); | ||
| 110 | + return null; | ||
| 111 | + } | ||
| 112 | + } | ||
| 113 | + | ||
| 114 | + /** | ||
| 115 | + * 反序列化复杂Collection如List<Bean>, 先使用createCollectionType()或contructMapType()构造类型, 然后调用本函数. | ||
| 116 | + * | ||
| 117 | + * @see #(Class, Class...) | ||
| 118 | + */ | ||
| 119 | + public <T> T fromJson(String jsonString, JavaType javaType) { | ||
| 120 | + if (StringUtils.isEmpty(jsonString)) { | ||
| 121 | + return null; | ||
| 122 | + } | ||
| 123 | + | ||
| 124 | + try { | ||
| 125 | + return mapper.readValue(jsonString, javaType); | ||
| 126 | + } catch (IOException e) { | ||
| 127 | + LOG.error(String.format("解析 JSON 字符串发生错误:%s", jsonString), e); | ||
| 128 | + return null; | ||
| 129 | + } | ||
| 130 | + } | ||
| 131 | + | ||
| 132 | + | ||
| 133 | +} |