java JAXB 解组集合

JAXB unmarshall a collection

提问by jwesonga

I have an XML doc:

我有一个 XML 文档：

<?xml version="1.0" encoding="UTF-8"?>

<Log>
    <logEntry>
       <severity>WARN</severity>
       <dateTime>2011-03-17 15:25</dateTime>
       <message>Here is the text from the application</message>
       <class>(class name)</class>
       <program> TB Reception</program>
    </logEntry>

    <logEntry>
       <severity>WARN</severity>
       <dateTime>2011-03-17 15:25</dateTime>
       <message>Here is the text from the application</message>
       <class>(class name)</class>
       <program> TB Reception</program>
    </logEntry>
</Log>

and two POJOs:

和两个 POJO：

package org.jwes.jaxb.jax;

import java.util.ArrayList;
import java.util.List;

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlElementWrapper;
import javax.xml.bind.annotation.XmlRootElement;

@XmlRootElement(name="Log")
public class Log {
    @XmlElementWrapper(name = "logEntry")
    private List<LogEntry> logList;

    public List<LogEntry> getLogEntries() {
        return logList;
    }

    public void setLogEntries(List<LogEntry> logList) {
        this.logList = logList;
    }


}

---

---

package org.jwes.jaxb.jax;

import java.io.Serializable;

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlElementWrapper;
import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;

@XmlRootElement(name="LogEntry")
public class LogEntry{


    private String source;
    private String message;
    private String severity;
    private String program;
    private String className;


    public String getSource() {
        return source;
    }
    public void setSource(String source) {
        this.source = source;
    }
    public String getMessage() {
        return message;
    }
    public void setMessage(String message) {
        this.message = message;
    }
    public String getSeverity() {
        return severity;
    }
    public void setSeverity(String severity) {
        this.severity = severity;
    }
    public String getProgram() {
        return program;
    }
    public void setProgram(String program) {
        this.program = program;
    }
    @XmlElement(name = "class")
    public String getClassName() {
        return className;
    }
    public void setClassName(String className) {
        this.className = className;
    }
}

I'd like to retrieve the values of the XML nodes using JAXB. I wrote this quick code:

我想使用 JAXB 检索 XML 节点的值。我写了这个快速代码：

public class App 
{
    public static void main( String[] args ) throws JAXBException, IOException
    {
        JAXBContext jc = JAXBContext.newInstance(Log.class);

        Unmarshaller um = jc.createUnmarshaller();
        Log logElement=(Log)um.unmarshal(new FileReader("src/main/resources/log.xml"));
        System.out.println(logElement.getLogEntries().toArray().length);


    }
}

When i run it I always get value of zero.

当我运行它时，我总是得到零值。

采纳答案by skaffman

You shouldn't be using @XmlElementWrapperhere, just @XmlElement:

你不应该@XmlElementWrapper在这里使用，只是@XmlElement：

@XmlRootElement(name="Log")
public class Log {
    @XmlElement(name = "logEntry")
    private List<LogEntry> logList;