java实现从文件中读取信息保存在Map中,修改Map中的值,将Map更新到文件中

时间:2022-12-16 09:03:57

package com.filetomap;

import Java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

/**
* 创建一个file,后缀名为cfg. 里面文本格式为每行:A=X结构,其中注释在最前面加上# 然后将该文件保存到map中(map(A,X);
*
* @author Administrator
*
*/
public class FileToMap1 {
private String line = System.getProperty(“line.separator”);
private String separ = “=”;
static String basePath = System.getProperty(“user.dir”);
static String filePath = “./Alms.cfg”;// 文件相对路径

public static void main(String[] args) {
FileToMap1 fileToMap1 = new FileToMap1();
Map<String, String> oldMap = fileToMap1.fTM();
Map<String, String> newMap = new HashMap<String, String>();
newMap.put("A", "A''");
Map<String, String> map = fileToMap1.newMapToOldMap(newMap, oldMap, false);
try {
fileToMap1.mapToFileDefault(map, new File(filePath), fileToMap1.separ);
} catch (IOException e) {
e.printStackTrace();
}
}

/**
* 有参构造函数
*
* @param separ
* @param filePath
*/
public FileToMap1(String separ, String filePath) {
this.filePath = filePath;
this.separ = separ;
File file = new File(filePath);
if (!file.exists()) {
System.out.println("文件不存在");
try {
file.createNewFile();
} catch (IOException e) {
System.out.println("路径:" + filePath + "创建失败");
e.printStackTrace();
}
}
}

/**
* 无参构造函数,用类默认的配置。
*/
public FileToMap1() {
File file = new File(filePath);
if (!file.exists()) {
System.out.println("文件不存在");
try {
file.createNewFile();
} catch (IOException e) {
System.out.println("路径:" + filePath + "创建失败");
e.printStackTrace();
}
}
}

/**
* 将map写入到file文件中。默认map(String A,String A')file中以A=A'来表示,map中每个键值对显示一行
* @throws IOException
*/
private File mapToFileDefault(Map<String, String> map,File file,String separ) throws IOException{
StringBuffer buffer = new StringBuffer();
FileWriter writer = new FileWriter(file, false);
for(Map.Entry entry:map.entrySet()){
String key = (String) entry.getKey();
String value = (String) entry.getValue();
buffer.append(key + "=" + value).append(line);
}
writer.write(buffer.toString());
writer.close();
return file;

}
/**
* 在newMap替换oldMap时,是否覆盖(isOverwrite)如果是,就直接替换,如果否,则将oldMap中的key前加“#”,默认为否
* @param newMap
* @param oldMap
* @return
*/
private Map<String, String> newMapToOldMapDefault(Map<String, String> newMap,Map<String, String> oldMap){
return newMapToOldMap(newMap,oldMap,false);
}

/**
* 在newMap替换oldMap时,是否覆盖(isOverwrite)如果是,就直接替换,如果否,则将oldMap中的key前加“#”,默认为否
*/
private Map<String, String> newMapToOldMap(Map<String, String> newMap,
Map<String, String> oldMap, boolean isOverwrite) {
// 由于oldMap中包含了file中更多内容,所以newMap中内容在oldMap中调整后,最后返回oldMap修改之后的map.
// 如果选择true覆盖相同的key
if (isOverwrite) {
// 循环遍历newMap
for (Map.Entry entry : newMap.entrySet()) {
String newKey = (String) entry.getKey();
String newValue = (String) entry.getValue();
oldMap.put(newKey, newValue);
}
} else {
// 不覆盖oldMap,需要在key相同的oldMap的key前加#;
// 循环遍历newMap
for (Map.Entry entry : newMap.entrySet()) {
String newKey = (String) entry.getKey();
String newValue = (String) entry.getValue();
String oldValue = oldMap.get(newKey);
oldMap.put("#" + newKey, oldValue);
oldMap.put(newKey, newValue);
}
}
return oldMap;
}

/**
* 将文件转换成map存储
*
* @return
*/
private Map<String, String> fTM() {
Map<String, String> map = new HashMap<String, String>();
File file = new File(filePath);
BufferedReader reader = null;
try {
System.out.println("以行为单位读取文件内容,一次读一整行:");
reader = new BufferedReader(new FileReader(file));
String tempString = null;
int line = 1;
// 一次读入一行,直到读入null为文件结束
while ((tempString = reader.readLine()) != null) {
// 显示行号
System.out.println("line " + line + ": " + tempString);
if (!tempString.startsWith("#")) {
String[] strArray = tempString.split("=");
map.put(strArray[0], strArray[1]);
}
line++;
}
reader.close();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException e1) {
}
}
}
for (Map.Entry entry : map.entrySet()) {
System.out.println(entry.getKey() + "=" + entry.getValue());
}
return map;
}

}