From b15036d2fdffa33a8583def95c9194b35ba42d4a Mon Sep 17 00:00:00 2001
From: 1099815072@qq.com <1099815072@qq.com>
Date: Fri, 13 Nov 2020 09:33:51 +0800
Subject: [PATCH] json工具类提交

---
 cloud/dahua/src/main/java/com/example/dahua/utils/JsonUtils.java | 133 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 133 insertions(+), 0 deletions(-)
 create mode 100644 cloud/dahua/src/main/java/com/example/dahua/utils/JsonUtils.java

diff --git a/cloud/dahua/src/main/java/com/example/dahua/utils/JsonUtils.java b/cloud/dahua/src/main/java/com/example/dahua/utils/JsonUtils.java
new file mode 100644
index 0000000..deb883e
--- /dev/null
+++ b/cloud/dahua/src/main/java/com/example/dahua/utils/JsonUtils.java
@@ -0,0 +1,133 @@
+package com.example.dahua.utils;
+
+import com.fasterxml.jackson.annotation.JsonInclude.Include;
+import com.fasterxml.jackson.core.type.TypeReference;
+import com.fasterxml.jackson.databind.DeserializationFeature;
+import com.fasterxml.jackson.databind.JavaType;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.apache.commons.lang.StringUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.util.Map;
+
+/**
+ * 类JsonMapper.java的实现描述：简单封装Jackson，实现JSON String<->Java Object的Mapper.
+ * 
+ * <p> 封装不同的输出风格, 使用不同的builder函数创建实例. </p>
+ * 
+ * @author xuquan
+ */
+public class JsonUtils {
+    
+    private static final Logger LOG = LoggerFactory.getLogger(JsonUtils.class);
+
+    private ObjectMapper mapper;
+
+    public JsonUtils(){
+        this(null);
+    }
+    
+    public JsonUtils(Include include) {
+        mapper = new ObjectMapper();
+        // 设置输出时包含属性的风格
+        if (include != null) {
+            mapper.setSerializationInclusion(include);
+        }
+        // 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
+        mapper.disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES);
+    }
+    
+    /**
+     * 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.
+     */
+    public static JsonUtils nonEmptyMapper() {
+        return new JsonUtils(Include.NON_EMPTY);
+    }
+
+    /**
+     * 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。
+     */
+    public static JsonUtils nonDefaultMapper() {
+        return new JsonUtils(Include.NON_DEFAULT);
+    }
+
+    /**
+     * Object可以是POJO，也可以是Collection或数组。
+     * 如果对象为Null, 返回"null".
+     * 如果集合为空集合, 返回"[]".
+     */
+    public String toJson(Object object) {
+
+        try {
+            return mapper.writeValueAsString(object);
+        } catch (IOException e) {
+            LOG.warn(String.format("序列化成 JSON 字符串发生错误:%s", object), e);
+            return null;
+        }
+    }
+
+    /**
+     * 反序列化POJO或简单Collection如List<String>.
+     * 
+     * 如果JSON字符串为Null或"null"字符串, 返回Null.
+     * 如果JSON字符串为"[]", 返回空集合.
+     * 
+     * 如需反序列化复杂Collection如List<MyBean>, 请使用fromJson(String, JavaType)
+     * 
+     * @see #fromJson(String, JavaType)
+     */
+    public <T> T fromJson(String jsonString, Class<T> clazz) {
+        if (StringUtils.isEmpty(jsonString)) {
+            return null;
+        }
+
+        try {
+            return mapper.readValue(jsonString, clazz);
+        } catch (IOException e) {
+            LOG.error(String.format("解析 JSON 字符串发生错误:%s", jsonString), e);
+            return null;
+        }
+    }
+    
+    /**
+     * 反序列化泛型对象
+     * @param <T>
+     * @param jsonString
+     * @param typeReference
+     * @return
+     */
+    public <T> T fromJson(String jsonString, TypeReference<T> typeReference) {
+        if (StringUtils.isEmpty(jsonString)) {
+            return null;
+        }
+
+        try {
+            return mapper.readValue(jsonString, typeReference);
+        } catch (IOException e) {
+            LOG.error(String.format("解析 JSON 字符串发生错误:%s", jsonString), e);
+            return null;
+        }
+    }
+
+    /**
+     * 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.
+     * 
+     * @see #(Class, Class...)
+     */
+    public <T> T fromJson(String jsonString, JavaType javaType) {
+        if (StringUtils.isEmpty(jsonString)) {
+            return null;
+        }
+
+        try {
+            return mapper.readValue(jsonString, javaType);
+        } catch (IOException e) {
+            LOG.error(String.format("解析 JSON 字符串发生错误:%s", jsonString), e);
+            return null;
+        }
+    }
+
+
+}
--
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