您可以使用声明式流映射 (DSM) https://mfatihercik.github.io/dsm流解析库可以轻松地将复杂的 XML 转换为 java 类。它使用 StAX 来解析 XML。
我跳过获取notes标签并在里面添加一个字段类_x_对象用于演示的标签。
这是 XML：
<?xml version="1.0" encoding="utf-8"?>
<root>
<notes />
<category_alpha>
<list_a>
<class_a_object>
<fieldA>A1</fieldA>
</class_a_object>
<class_a_object>
<fieldA>A2</fieldA>
</class_a_object>
<class_a_object>
<fieldA>A3</fieldA>
</class_a_object>
</list_a>
<list_b>
<class_b_object>
<fieldB>B1</fieldB>
</class_b_object>
<class_b_object>
<fieldB>B2</fieldB>
</class_b_object>
<class_b_object>
<fieldB>B3</fieldB>
</class_b_object>
</list_b>
</category_alpha>
<category_beta>
<class_c_object>
<fieldC>C1</fieldC>
</class_c_object>
<class_c_object>
<fieldC>C2</fieldC>
</class_c_object>
<class_c_object>
<fieldC>C3</fieldC>
</class_c_object>
</category_beta>
</root>
首先，您必须以 yaml 或 JSON 格式定义 XML 数据和类字段之间的映射。
以下是映射定义：
result:
type: object
path: /root
fields:
listOfA:
type: array
path: .*class_a_object # path is regex
fields:
fieldOfA:
path: fieldA
listOfB:
type: array
path: .*class_b_object
fields:
fieldOfB:
path: fieldB
listOfC:
type: array
path: .*class_c_object
fields:
fieldOfC:
path: fieldC
您想要反序列化的 Java 类：
public class Root {
public List<A> listOfA;
public List<B> listOfB;
public List<C> listOfC;
public static class A{
public String fieldOfA;
}
public static class B{
public String fieldOfB;
}
public static class C{
public String fieldOfC;
}
}
解析XML的Java代码：
DSM dsm=new DSMBuilder(new File("path/to/mapping.yaml")).setType(DSMBuilder.TYPE.XML).create(Root.class);
Root root = (Root)dsm.toObject(xmlFileContent);
// write root object as json
dsm.getObjectMapper().writerWithDefaultPrettyPrinter().writeValue(System.out, object);
这是输出：
{
"listOfA" : [ {"fieldOfA" : "A1"}, {"fieldOfA" : "A2"}, {"fieldOfA" : "A3"} ],
"listOfB" : [ {"fieldOfB" : "B1"}, {"fieldOfB" : "B2"}, "fieldOfB" : "B3"} ],
"listOfC" : [ {"fieldOfC" : "C1"}, {"fieldOfC" : "C2"}, {"fieldOfC" : "C3"} ]
}
UPDATE:
据我从您的评论中了解到，您希望将大型 XML 文件作为流读取。并在读取文件时处理数据。
DSM 允许您在读取 XML 的同时处理数据。
声明三个不同的函数来处理部分数据。
FunctionExecutor processA=new FunctionExecutor(){
@Override
public void execute(Params params) {
Root.A object=params.getCurrentNode().toObject(Root.A.class);
// process aClass; save to db. call service etc.
}
};
FunctionExecutor processB=new FunctionExecutor(){
@Override
public void execute(Params params) {
Root.B object=params.getCurrentNode().toObject(Root.B.class);
// process aClass; save to db. call service etc.
}
};
FunctionExecutor processC=new FunctionExecutor(){
@Override
public void execute(Params params) {
Root.C object=params.getCurrentNode().toObject(Root.C.class);
// process aClass; save to db. call service etc.
}
};
向 DSM 注册功能
DSMBuilder builder = new DSMBuilder(new File("path/to/mapping.yaml")).setType(DSMBuilder.TYPE.XML);
// register function
builder.registerFunction("processA",processA);
builder.registerFunction("processB",processB);
builder.registerFunction("processC",processC);
DSM dsm= builder.create();
Object object = dsm.toObject(xmlContent);
更改映射文件以调用注册函数
result:
type: object
path: /root
fields:
listOfA:
type: object
function: processA # when 'class_a_object' tag closed processA function will be executed.
path: .*class_a_object # path is regex
fields:
fieldOfA:
path: fieldA
listOfB:
type: object
path: .*class_b_object
function: processB# register function
fields:
fieldOfB:
path: fieldB
listOfC:
type: object
path: .*class_c_object
function: processC# register function
fields:
fieldOfC:
path: fieldC
