JAVA 反射应用：properties2Object

MixAll.java

import java.lang.reflect.Method;
import java.util.Properties;

public class MixAll {

    /**
     * 将Properties中的值写入Object
     */
    public static void properties2Object(final Properties p, final Object object) {
        Method[] methods = object.getClass().getMethods();
        for (Method method : methods) {
            String mn = method.getName();
            if (mn.startsWith("set")) {
                try {
                    String tmp = mn.substring(4);
                    String first = mn.substring(3, 4);

                    String key = first.toLowerCase() + tmp;
                    String property = p.getProperty(key);
                    if (property != null) {
                        Class<?>[] pt = method.getParameterTypes();
                        if (pt != null && pt.length > 0) {
                            String cn = pt[0].getSimpleName();
                            Object arg = null;
                            if (cn.equals("int")) {
                                arg = Integer.parseInt(property);
                            } else if (cn.equals("long")) {
                                arg = Long.parseLong(property);
                            } else if (cn.equals("double")) {
                                arg = Double.parseDouble(property);
                            } else if (cn.equals("boolean")) {
                                arg = Boolean.parseBoolean(property);
                            } else if (cn.equals("String")) {
                                arg = property;
                            } else {
                                continue;
                            }
                            method.invoke(object, new Object[] { arg });
                        }
                    }
                } catch (Throwable e) {
                }
            }
        }
    }

}

PersonConfig.java

public class PersonConfig {

    private String name;
    private int age;
    private double saving;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public double getSaving() {
        return saving;
    }

    public void setSaving(double saving) {
        this.saving = saving;
    }

    @Override
    public String toString() {
        return "PersonConfig [name=" + name + ", age=" + age + ", saving="
                + saving + "]";
    }
}

TestCommandline.java

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;

import org.apache.commons.cli.CommandLine;
import org.apache.commons.cli.CommandLineParser;
import org.apache.commons.cli.DefaultParser;
import org.apache.commons.cli.Option;
import org.apache.commons.cli.Options;
import org.apache.commons.cli.ParseException;

public class TestCommandline {
    public static void main(String[] args) throws ParseException, IOException {
        Options options = new Options();
        Option opt = new Option("c", "config", true, "config file path");
        opt.setRequired(true);
        options.addOption(opt);

        CommandLineParser parser = new DefaultParser();
        CommandLine commandLine = parser.parse(options, args);

        String optNmae = "c";
        if (commandLine.hasOption(optNmae)) {
            File file = new File(commandLine.getOptionValue(optNmae));

            InputStream in = new BufferedInputStream(new FileInputStream(file));
            Properties properties = new Properties();
            properties.load(in);

            PersonConfig personConfig = new PersonConfig();
            System.out.println(personConfig); // 前
            MixAll.properties2Object(properties, personConfig);
            System.out.println(personConfig); // 后

            System.out.println("load config properties file OK, " + file);
            in.close();
        }
    }
}

E:configperson.properties

name=Zno
age=18
saving=200.0

执行参数：

-c E:/config/person.properties

运行结果：

PersonConfig [name=null, age=0, saving=0.0]
PersonConfig [name=Zno, age=18, saving=200.0]
load config properties file OK, E:configperson.properties

动态修改属性

　　　 　import org.apache.commons.beanutils.BeanUtils;

        public void clean() {
            Field[] fields = this.getClass().getDeclaredFields();
            for (Field field : fields) {
                try {
                    String name = field.getName();
                    String property = BeanUtils.getProperty(this, name);
                    if ("未知".equals(property)) {
                        BeanUtils.setProperty(this, name, null);
                    }
                } catch (Exception e) {
                }
            }
        }

清洗更新数据，提高更新效率，避免无修改却被更新

    public static <T> void clean4update(T dataFromDb, T data4update, String ... ignores) {
        List<String> ignoreList = null;
        if(ignores != null) {
            ignoreList = Arrays.asList(ignores);
        }
        Class<? extends Object> clazz = dataFromDb.getClass();
        Set<String> fieldSet = new HashSet<String>();
        Map<String, Method> methodMap = new HashMap<String, Method>();
        Field[] fields = clazz.getDeclaredFields();
        Object[] args = new Object[] {};
        Object[] args2 = new Object[] { null };
        for (Field field : fields) {
            String name = field.getName();
            fieldSet.add(name);
        }
        Method[] methods = clazz.getMethods();
        for (Method method : methods) {
            String mn = method.getName();
            if (mn.startsWith("get") || mn.startsWith("set")) {
                String tmp = mn.substring(4);
                String first = mn.substring(3, 4);
                String key = first.toLowerCase() + tmp;
                if(ignoreList.contains(key)) {
                    continue;
                }
                if (!fieldSet.contains(key)) {
                    continue;
                }
                methodMap.put(key + (mn.startsWith("get") ? ":g" : ":s"), method);
            }
        }

        Set<Entry<String, Method>> entrySet = methodMap.entrySet();
        for (Entry<String, Method> entry : entrySet) {
            String key = entry.getKey();
            Method method = entry.getValue();
            if (key.endsWith(":s")) {
                continue;
            }
            try {
                Object invoke = method.invoke(dataFromDb, args);
                if (invoke == null) {
                    continue;
                }
                boolean isSame = invoke.equals(method.invoke(data4update, args));
                if (isSame) {
                    methodMap.get(key.replace(":g", ":s")).invoke(data4update, args2);
                }//TODO 可以设置一个返回值，除了忽略的字段，如果所有getter对应的值都相同，则返回true，有一处不同即可设置为false 
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            } catch (IllegalArgumentException e) {
                e.printStackTrace();
            } catch (InvocationTargetException e) {
                e.printStackTrace();
            }
        }
    }

测试：

    @Test
    public void testclean4update() {
        Foo dataFromDb = new Foo();
        Date date = new Date();
        
        dataFromDb.setGmtCreate(date);
        dataFromDb.setGmtModified(date);
        dataFromDb.setPageName("啊啊啊啊");
        dataFromDb.setPagePerms("/aaaa,/bbbb");
        dataFromDb.setPageType(1);
        dataFromDb.setPageUri("/sdfsd/sdfsdf");
        dataFromDb.setRemarks("lljkjkljkjl");
        dataFromDb.setS01Id(1L);
        dataFromDb.setS02Id(2L);
        Foo data4update = new Foo();
        data4update.setGmtCreate(date);
        data4update.setGmtModified(DateUtils.delaySec(date, 2));
        data4update.setPageName("啊啊啊啊");
        data4update.setPagePerms("/aaaa,/bbbb1");
        data4update.setPageType(2);
        data4update.setPageUri("/sdfsd/sdfsdf");
        data4update.setRemarks("lljkjkljkjl");
        data4update.setS01Id(1L);
        data4update.setS02Id(2L);
        SqlUtils.clean4update(dataFromDb, data4update, "s02Id");
        System.out.println(JSONObject.toJSONString(data4update));;
    }

    public static class Foo {
        /** 自增主键 */
        private Long s02Id;

        /** 子系统主键，即外键 */
        private Long s01Id;

        /** 修改时间 */
        private Date gmtModified;

        /** 创建时间 */
        private Date gmtCreate;

        /** 页面名称 */
        private String pageName;

        /** 页面uri，该页面前端访问地址 */
        private String pageUri;

        /** 页面权限列表，英文逗号分隔/aaa，/bbb （可以为空） */
        private String pagePerms;

        /** 页面类型，1 需绑定到菜单，2游离页面 */
        private Integer pageType;

        /** 备注 */
        private String remarks;

        public Long getS02Id() {
            return s02Id;
        }

        public void setS02Id(Long s02Id) {
            this.s02Id = s02Id;
        }

        public Long getS01Id() {
            return s01Id;
        }

        public void setS01Id(Long s01Id) {
            this.s01Id = s01Id;
        }

        public Date getGmtModified() {
            return gmtModified;
        }

        public void setGmtModified(Date gmtModified) {
            this.gmtModified = gmtModified;
        }

        public Date getGmtCreate() {
            return gmtCreate;
        }

        public void setGmtCreate(Date gmtCreate) {
            this.gmtCreate = gmtCreate;
        }

        public String getPageName() {
            return pageName;
        }

        public void setPageName(String pageName) {
            this.pageName = pageName;
        }

        public String getPageUri() {
            return pageUri;
        }

        public void setPageUri(String pageUri) {
            this.pageUri = pageUri;
        }

        public String getPagePerms() {
            return pagePerms;
        }

        public void setPagePerms(String pagePerms) {
            this.pagePerms = pagePerms;
        }

        public Integer getPageType() {
            return pageType;
        }

        public void setPageType(Integer pageType) {
            this.pageType = pageType;
        }

        public String getRemarks() {
            return remarks;
        }

        public void setRemarks(String remarks) {
            this.remarks = remarks;
        }

        @Override
        public String toString() {
            StringBuilder sb = new StringBuilder();
            sb.append(getClass().getSimpleName());
            sb.append(" [");
            sb.append("Hash = ").append(hashCode());
            sb.append(", s02Id=").append(s02Id);
            sb.append(", s01Id=").append(s01Id);
            sb.append(", gmtModified=").append(gmtModified);
            sb.append(", gmtCreate=").append(gmtCreate);
            sb.append(", pageName=").append(pageName);
            sb.append(", pageUri=").append(pageUri);
            sb.append(", pagePerms=").append(pagePerms);
            sb.append(", pageType=").append(pageType);
            sb.append(", remarks=").append(remarks);
            sb.append("]");
            return sb.toString();
        }
    }

输出：

{"gmtModified":1615891950943,"pagePerms":"/aaaa,/bbbb1","pageType":2,"s02Id":2}