最近，研究map与java对象之间的相互转换，总结了5种方法：
第一种：使用org.apache.commons.beanutils转换
用到的主要jar包：commons-beanutils-1.9.3.jar
//map转java对象
public static object maptoobject(map map, class beanclass)
throws exception {
if (map == null) {
return null;
}
object obj = beanclass.newinstance();
beanutils.populate(obj, map);
return obj;
}
//java对象转map
public static map objecttomap(object obj) {
if (obj == null)
return null;
return new beanmap(obj);
} 在使用该方法进行java对象转map时，可能会发生以下错误：
exception in thread "main" java.lang.noclassdeffounderror: org/apache/commons/collections/transformer
at java.lang.classloader.defineclass1(native method)
at java.lang.classloader.defineclass(classloader.java:621)
at java.security.secureclassloader.defineclass(secureclassloader.java:124)
at java.net.urlclassloader.defineclass(urlclassloader.java:260)
at java.net.urlclassloader.access$000(urlclassloader.java:56)
at java.net.urlclassloader$1.run(urlclassloader.java:195)
at java.security.accesscontroller.doprivileged(native method)
at java.net.urlclassloader.findclass(urlclassloader.java:188)
at java.lang.classloader.loadclass(classloader.java:307)
at sun.misc.launcher$appclassloader.loadclass(launcher.java:301)
at java.lang.classloader.loadclass(classloader.java:252)
at java.lang.classloader.loadclassinternal(classloader.java:320)
at org.apache.commons.beanutils.beanmap.createtypetransformers(beanmap.java:132)
at org.apache.commons.beanutils.beanmap.(beanmap.java:68)
at com.example2.pojo.pojotomap.objecttomap(pojotomap.java:23)
at com.example2.pojo.pojotomap.main(pojotomap.java:16)
caused by: java.lang.classnotfoundexception: org.apache.commons.collections.transformer
at java.net.urlclassloader$1.run(urlclassloader.java:200)
at java.security.accesscontroller.doprivileged(native method)
at java.net.urlclassloader.findclass(urlclassloader.java:188)
at java.lang.classloader.loadclass(classloader.java:307)
at sun.misc.launcher$appclassloader.loadclass(launcher.java:301)
at java.lang.classloader.loadclass(classloader.java:252)
at java.lang.classloader.loadclassinternal(classloader.java:320)
... 16 more
解决方法见本人的另一篇文章： https://blog.csdn.net/liuyunyihao/article/details/86596595
第二种：使用introspector转换
//map转java对象
public static object maptoobject(map map, class beanclass) throws exception {
if (map == null)
return null;
object obj = beanclass.newinstance();
beaninfo beaninfo = introspector.getbeaninfo(obj.getclass());
propertydescriptor[] propertydescriptors = beaninfo.getpropertydescriptors();
for (propertydescriptor property : propertydescriptors) {
method setter = property.getwritemethod();
if (setter != null) {
setter.invoke(obj, map.get(property.getname()));
}
}
return obj;
}
//java对象转map
public static map objecttomap(object obj) throws exception {
if (obj == null) {
return null;
}
map map = new hashmap();
beaninfo beaninfo = introspector.getbeaninfo(obj.getclass());
propertydescriptor[] propertydescriptors = beaninfo
.getpropertydescriptors();
for (propertydescriptor property : propertydescriptors) {
string key = property.getname();
if (key.comparetoignorecase("class") == 0) {
continue;
}
method getter = property.getreadmethod();
object value = getter != null ? getter.invoke(obj) : null;
map.put(key, value);
}
return map;
} 第三种：使用reflect转换
//map转java对象
public static object maptoobject(map map, class beanclass) throws exception {
if (map == null) {
return null;
}
object object = beanclass.newinstance();
field[] fields = beanclass.getdeclaredfields();
for (field field : fields) {
int mod = field.getmodifiers();
if (modifier.isfinal(mod) || modifier.isstatic(mod)) {
continue;
}
field.setaccessible(true);
field.set(object, map.get(field.getname()));
}
return object;
}
//java对象转map
public static map objecttomap(object obj) throws exception {
if (obj == null) {
return null;
}
map map = new hashmap();
field[] declaredfields = obj.getclass().getdeclaredfields();
for (field field : declaredfields) {
field.setaccessible(true);
map.put(field.getname(), field.get(obj));
}
return map;
} 第四种：使用net.sf.cglib.beans.beanmap转换
用到的主要jar包：cglib-2.2.2.jar
//map转java对象
public static object maptoobject(map map, class beanclass) throws exception {
object object = beanclass.newinstance();
beanmap beanmap = beanmap.create(object);
beanmap.putall(map);
return object;
}
//java对象转map
public static map objecttomap(object obj) {
map map = maps.newhashmap();
if (obj != null) {
beanmap beanmap = beanmap.create(obj);
for (object key : beanmap.keyset()) {
map.put(key "", beanmap.get(key));
}
}
return map;
} 在使用本方法进行map转java对象时，可能会发生以下错误：
exception in thread "main" java.lang.noclassdeffounderror: org/objectweb/asm/type
at net.sf.cglib.core.typeutils.parsetype(typeutils.java:184)
at net.sf.cglib.core.keyfactory.(keyfactory.java:66)
at net.sf.cglib.beans.beanmap$generator.(beanmap.java:64)
at net.sf.cglib.beans.beanmap.create(beanmap.java:56)
at com.example2.pojo.maptopojo.maptobean(maptopojo.java:27)
at com.example2.pojo.maptopojo.main(maptopojo.java:18)
caused by: java.lang.classnotfoundexception: org.objectweb.asm.type
at java.net.urlclassloader$1.run(urlclassloader.java:200)
at java.security.accesscontroller.doprivileged(native method)
at java.net.urlclassloader.findclass(urlclassloader.java:188)
at java.lang.classloader.loadclass(classloader.java:307)
at sun.misc.launcher$appclassloader.loadclass(launcher.java:301)
at java.lang.classloader.loadclass(classloader.java:252)
at java.lang.classloader.loadclassinternal(classloader.java:320)
... 6 more 解决方法见本人的另一篇文章：https://blog.csdn.net/liuyunyihao/article/details/86593722
第五种：使用json转换
用到的主要jar包：fastjson-1.2.54.jar
//map转java对象
public static object maptoobject(map map, class beanclass) throws exception {
string jsonstr = jsonobject.tojsonstring(map);
return jsonobject.parseobject(jsonstr, beanclass);
}
//java对象转map
public static map objecttomap(object obj) {
string jsonstr = jsonobject.tojsonstring(obj);
return jsonobject.parseobject(jsonstr);
} 以上方法本人均实际测试通过。