自动生成构造方法、getter、setter

前言

​ 一直很想知道IDE是如何自动去生成类的构造和getter、setter方法，大概是有个想法，获取当前的类，利用反射去获取属性名和类型，然后生成，所以我想自己试试。

写个模板类

package common;
public class Templates {
	public static final String T_CLASS 		= "package {0};\n\n{1}public class {2} {\n\n{3}\n\n{5}\n\n{4}\n}";
	public static final String T_GET   		= "\tpublic {0} get{1} () {\n\t\treturn {2};\n\t}\n";
	public static final String T_SET   		= "\tpublic void set{0}({1} {2}) {\n\t\tthis.{2}={2};\n\t}\n";
	public static final String T_ATTR1  	= "\tprivate {0} {1};\n";
	public static final String T_ATTR2  	= "\t\tthis.{0}={0};\n";
	public static final String T_IMPORT 	= "import java.util.Date;\n\n";
	public static final String T_CONSTRUCT 	= "\tpublic {0}({1}) {\n\t\tsuper();\n{2}\n\t}\n";
	public static String format(String pattern, String ... arguments){
		String format = pattern;
		for(int i=0;i<arguments.length;i++){
			format = format.replace("{"+i+"}",arguments[i]);
		}
		return format;
	}
	public static String loadTemplate(String clazz,String pack,String port,
							String attrs,String get_set,String construct){
		return format(T_CLASS, clazz,pack,port,attrs,get_set,construct);
	}
}

创建一个实体类

package cc.vvxtoys.pojo;
public class Student {
	private int id;
	private String name;
	private String sex;
	private String school;
}

工具类

package common;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import org.apache.log4j.Logger;
public class Common {
	private static Logger log = Logger.getLogger(Common.class);
	//获得绝对路径
	public static String absolutePath(String pack, String name, String suffix) {
		List<String> list = new ArrayList<>();
		String absolutePath = "";
		try {
			String packPath = pack.replace(".", "\\");
			File src = new File(".\\src");
			File file = new File(src.getCanonicalPath());
			File[] fs = file.listFiles();
			for (int i = 0; i < fs.length; i++) {
				if (fs[i].isDirectory()) {
					if (fs[i].getAbsolutePath().endsWith(packPath)) {
						absolutePath = fs[i].getAbsolutePath() + "\\" + name + suffix;
						return absolutePath;
					}
					list.add(fs[i].getAbsolutePath());
				}
			}
			for (int j = 0; j < Integer.MAX_VALUE; j++) {
				if (j>0&&j == list.size() - 1) {
					break;
				}
				File tmp = new File(list.get(j));
				fs = tmp.listFiles();
				for (int k = 0; k < fs.length; k++) {
					if (fs[k].isDirectory()) {
						if (fs[k].getAbsolutePath().endsWith(packPath)) {
							absolutePath = fs[k].getAbsolutePath() + "\\" + name + suffix;
							return absolutePath;
						}
						list.add(fs[k].getAbsolutePath());
					}
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		return absolutePath;
	}
	public static String loadFile(String path) {
		File file = new File(path);
		String str = null;
		BufferedReader reader = null;
		StringBuffer buffer = new StringBuffer();
		String charset = "utf-8";
		try {
			InputStreamReader is = new InputStreamReader(new FileInputStream(file), charset);
			reader = new BufferedReader(is);
			while ((str = reader.readLine()) != null) {
				buffer.append(str);
				buffer.append("\n");
			}
		} catch (IOException e) {
			e.printStackTrace();
		} finally {
			if (reader != null) {
				try {
					reader.close();
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		}
		return buffer.toString();
	}
	public static void writeFile(String filePath, String str, boolean flg) {
		try {
			FileWriter fw = new FileWriter(new File(filePath), flg);
			PrintWriter pw = new PrintWriter(fw);
			pw.println(str);
			log.info("写入成功。。。");
			pw.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	public static void writeFile(String filePath, String str) {
		try {
			FileWriter fw = new FileWriter(new File(filePath), true);
			PrintWriter pw = new PrintWriter(fw);
			pw.println(str);
			log.info("写入成功。。。");
			pw.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	//首字母大写
	public static String upInitials(String str){
		StringBuffer buff = new StringBuffer();
		buff.append(String.valueOf(str.charAt(0)).toUpperCase());
		buff.append(str.toCharArray(),1,str.length()-1);
		return buff.toString();
	}
}

构建类

package auto_get_set;
import java.lang.reflect.Field;
import common.Common;
import common.Templates;
/**
 * @author vvxtoys
 */
public class ClassGenerator {
	private String [] attrs;
	private String [] types;
	private String absolutePath;
	private String context;
	private String clazz;
	public ClassGenerator(Object obj) {
		loadClass(obj);
	}
	public void loadClass(Object obj){
		Field [] fs = null;
		try{
			String claname = obj.getClass().getSimpleName();
			String suffix = ".java";
			String pack   = obj.getClass().getPackage().getName();
			absolutePath = Common.absolutePath(pack, claname, suffix);
			context = Common.loadFile(absolutePath);
			clazz = claname;
			Class clazz = Class.forName(obj.getClass().getName());
			fs = clazz.getDeclaredFields();
			attrs = new String[fs.length];
			types = new String[fs.length];
			for(int i=0;i<fs.length;i++){
				attrs[i] = fs[i].getName();
				types[i] = fs[i].getType().getSimpleName();
			}
		}catch(Exception e){
			e.printStackTrace();
		}
	}
	public void autoGetSet(){
		String str = context.substring(0,context.lastIndexOf("}"));
		String get_set = "";
		for(int i=0;i<attrs.length;i++){
			String g1 = Templates.format(Templates.T_GET, types[i],Common.upInitials(attrs[i]),attrs[i]);
			String s1 = Templates.format(Templates.T_SET, Common.upInitials(attrs[i]),types[i],attrs[i]);
			get_set+=g1+s1;
		}
		str+=get_set;
		str+="}";
		context = str;
	}
	public void autoConstruct(){
		String str = context.substring(0,context.lastIndexOf("}"));
		String c1 = Templates.format(Templates.T_CONSTRUCT, clazz,"","");
		String params = "";
		String field = "";
		for(int i=0;i<attrs.length;i++){
			params+=types[i]+" "+attrs[i]+",";
			field+=Templates.format(Templates.T_ATTR2, attrs[i]);
		}
		params = params.substring(0,params.length()-1);
		String c2 = Templates.format(Templates.T_CONSTRUCT, clazz,params,field);
		str +=c1+c2;
		str+="}";
		context = str;
	}
	public void updateClass(){
		Common.writeFile(absolutePath, context,false);
	}
	public void run(){
		autoConstruct();
		autoGetSet();
		updateClass();
	}
}

测试

package auto_get_set;
import cc.vvxtoys.pojo.Student;
public class Test {
	public static void main(String[] args) {
		ClassGenerator g = new ClassGenerator(new Student());
		g.run();
	}
}

构建之后的实体类

package cc.vvxtoys.pojo;
public class Student {
	private int id;
	private String name;
	private String sex;
	private String school;
	public Student() {
		super();
	}
	public Student(int id,String name,String sex,String school) {
		super();
		this.id=id;
		this.name=name;
		this.sex=sex;
		this.school=school;
	}
	public int getId () {
		return id;
	}
	public void setId(int id) {
		this.id=id;
	}
	public String getName () {
		return name;
	}
	public void setName(String name) {
		this.name=name;
	}
	public String getSex () {
		return sex;
	}
	public void setSex(String sex) {
		this.sex=sex;
	}
	public String getSchool () {
		return school;
	}
	public void setSchool(String school) {
		this.school=school;
	}
}

结束

写写停停大概也是花费了两天的时间，东西虽然很小，也还有bug，但是还是有点成就感的。我知道IDE肯定不可能用这么蠢得实现方式，但是以我现在的想法只能这样了，还是需要多学点东西，然后我再重构这些代码。