在项目中，我们很多都用到了xml文件，无论是参数配置还是与其它系统的数据交互。今天就来讲一下Java 中使用dom4j来操作XML文件。
1. 将XML文件的内容转化为String
public static String doc2String(Document document) {
String s = "";
try {
ByteArrayOutputStream out = new ByteArrayOutputStream();
OutputFormat format = new OutputFormat(" ", true, "GB2312");
XMLWriter writer = new XMLWriter(out, format);
writer.write(document);
s = out.toString("GB2312");
} catch(Exception ex) {
ex.printStackTrace();
}
return s;
}2. 将符合XML格式的String 转化为XML Document
public static Document string2Document(String s) {
Document doc = null;
try {
doc = DocumentHelper.parseText(s);
} catch(Exception ex) {
ex.printStackTrace();
}
return doc;
}3. 将Document对象保存为一个xml文件到本地
public static boolean doc2XmlFile(Document document, String filename) {
boolean flag = true;
try {
OutputFormat format = OutputFormat.createPrettyPrint();
format.setEncoding("GB2312");
XMLWriter writer = new XMLWriter(new FileWriter(new File(filename)),format);
writer.write(document);
writer.close();
} catch(Exception ex) {
flag = false;
ex.printStackTrace();
}
return flag;
}4. 将xml格式的字符串保存为本地文件，如果字符串格式不符合xml规则，则返回失败
public static boolean string2XmlFile(String str, String filename) {
boolean flag = true;
try {
Document doc = DocumentHelper.parseText(str);
flag = doc2XmlFile(doc, filename);
} catch(Exception ex) {
flag = false;
ex.printStackTrace();
}
return flag;
}5. 载入一个xml文档
public static Document load(String filename) {
Document document = null;
try {
SAXReader saxReader = new SAXReader();
document = saxReader.read(new File(filename));
} catch(Exception ex) {
ex.printStackTrace();
}
return document;
}6. 演示String保存为xml文件
public void xmlWriteDemoByString() {
String s = "<test>test</test>";
string2XmlFile(s, "xmlWriteDemoByString.xml");
string2XmlFile(s, "classes/xmlWriteDemoByString.xml");
}7. 演示手动创建一个Document，并保存为XML文件
public void xmlWriteDemoByDocument() {
Document document = DocumentHelper.createDocument();
Element configElement = document.addElement("config");
configElement.addComment("东电ftp配置");
Element ftpElement = configElement.addElement("ftp");
ftpElement.addAttribute("name", "DongDian");
Element hostElement = ftpElement.addElement("ftp-host");
hostElement.setText("127.0.0.1");
(ftpElement.addElement("ftp-port")).setText("21");
(ftpElement.addElement("ftp-user")).setText("cxl");
(ftpElement.addElement("ftp-pwd")).setText("longshine");
ftpElement.addComment("ftp最多尝试连接次数");
(ftpElement.addElement("ftp-try")).setText("50");
ftpElement.addComment("ftp尝试连接延迟时间");
(ftpElement.addElement("ftp-delay")).setText("10");
doc2XmlFile(document, "classes/xmlWriteDemoByDocument.xml");
}8. 演示读取文件的具体某个节点的值
public static void xmlReadDemo() {
Document doc = load("classes/xmlWriteDemoByDocument.xml");
List list = doc.selectNodes("/config/ftp");
Iterator it = list.iterator();
while(it.hasNext()) {
Element ftpElement = (Element)it.next();
System.out.println("ftp_name="+ ftpElement.attribute("name").getValue());
}
list = doc.selectNodes("/config/ftp/@name");
it = list.iterator();
while(it.hasNext()) {
Attribute attribute = (Attribute)it.next();
System.out.println("@name="+ attribute.getValue());
}
list = doc.selectNodes("/config/ftp/ftp-host");
it = list.iterator();
Element hostElement = (Element)it.next();
System.out.println("DongDian's ftp_host="+ hostElement.getText());
}9. 修改或删除某个值或属性
ftpElement.remove(hostElement);
ftpElement.remove(nameAttribute);
hostElement.setText("192.168.0.1");
nameAttribute.setValue("ChiFeng");
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