请教actionservlet填充actionform的实现原理

Question

没看过源代码。
你可以去看看他源代码(估计和下面一样)。
你可以用apache的commons类库BeanUtils来完成这个自动填充的功能 :)

Answer 1

谢谢回复,能列一下BeanUtils的实现代码吗

Answer 2

// Decompiled by Jad v1.5.7g. Copyright 2000 Pavel Kouznetsov.
// Jad home page: http://www.geocities.com/SiliconValley/Bridge/8617/jad.html
// Decompiler options: packimports(3) fieldsfirst ansi 
// Source File Name:   BeanUtils.javapackage org.apache.commons.beanutils;import java.beans.IndexedPropertyDescriptor;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Array;
import java.lang.reflect.InvocationTargetException;
import java.util.*;
import org.apache.commons.collections.FastHashMap;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;// Referenced classes of package org.apache.commons.beanutils:
//            DynaBean, MappedPropertyDescriptor, PropertyUtils, DynaClass, 
//            DynaProperty, ConvertUtils, Converterpublic class BeanUtils
{    private static FastHashMap dummy = new FastHashMap();
    private static Log log;
    private static int debug = 0;
    static Class class$org$apache$commons$beanutils$BeanUtils; /* synthetic field */    public BeanUtils()
    {
    }    public static int getDebug()
    {
        return debug;
    }    public static void setDebug(int newDebug)
    {
        debug = newDebug;
    }    public static Object cloneBean(Object bean)
        throws IllegalAccessException, InstantiationException, InvocationTargetException, NoSuchMethodException
    {
        if(log.isDebugEnabled())
            log.debug("Cloning bean: " + bean.getClass().getName());
        Class clazz = bean.getClass();
        Object newBean = clazz.newInstance();
        PropertyUtils.copyProperties(newBean, bean);
        return newBean;
    }    public static void copyProperties(Object dest, Object orig)
        throws IllegalAccessException, InvocationTargetException
    {
        if(dest == null)
            throw new IllegalArgumentException("No destination bean specified");
        if(orig == null)
            throw new IllegalArgumentException("No origin bean specified");
        if(log.isDebugEnabled())
            log.debug("BeanUtils.copyProperties(" + dest + ", " + orig + ")");
        if(orig instanceof DynaBean)
        {
            DynaProperty origDescriptors[] = ((DynaBean)orig).getDynaClass().getDynaProperties();
            for(int i = 0; i < origDescriptors.length; i++)
            {
                String name = origDescriptors[i].getName();
                if(PropertyUtils.isWriteable(dest, name))
                {
                    Object value = ((DynaBean)orig).get(name);
                    copyProperty(dest, name, value);
                }
            }        } else
        if(orig instanceof Map)
        {
            for(Iterator names = ((Map)orig).keySet().iterator(); names.hasNext();)
            {
                String name = (String)names.next();
                if(PropertyUtils.isWriteable(dest, name))
                {
                    Object value = ((Map)orig).get(name);
                    copyProperty(dest, name, value);
                }
            }        } else
        {
            PropertyDescriptor origDescriptors[] = PropertyUtils.getPropertyDescriptors(orig);
            for(int i = 0; i < origDescriptors.length; i++)
            {
                String name = origDescriptors[i].getName();
                if(!"class".equals(name) && PropertyUtils.isReadable(orig, name) && PropertyUtils.isWriteable(dest, name))
                    try
                    {
                        Object value = PropertyUtils.getSimpleProperty(orig, name);
                        copyProperty(dest, name, value);
                    }
                    catch(NoSuchMethodException e) { }
            }        }
    }

Answer 3

public static void copyProperty(Object bean, String name, Object value)
        throws IllegalAccessException, InvocationTargetException
    {
        if(log.isTraceEnabled())
        {
            StringBuffer sb = new StringBuffer("  copyProperty(");
            sb.append(bean);
            sb.append(", ");
            sb.append(name);
            sb.append(", ");
            if(value == null)
                sb.append("<NULL>");
            else
            if(value instanceof String)
                sb.append((String)value);
            else
            if(value instanceof String[])
            {
                String values[] = (String[])value;
                sb.append('[');
                for(int i = 0; i < values.length; i++)
                {
                    if(i > 0)
                        sb.append(',');
                    sb.append(values[i]);
                }                sb.append(']');
            } else
            {
                sb.append(value.toString());
            }
            sb.append(')');
            log.trace(sb.toString());
        }
        Object target = bean;
        int delim = name.lastIndexOf(46);
        if(delim >= 0)
        {
            try
            {
                target = PropertyUtils.getProperty(bean, name.substring(0, delim));
            }
            catch(NoSuchMethodException e)
            {
                return;
            }
            name = name.substring(delim + 1);
            if(log.isTraceEnabled())
            {
                log.trace("    Target bean = " + target);
                log.trace("    Target name = " + name);
            }
        }
        String propName = null;
        Class type = null;
        int index = -1;
        String key = null;
        propName = name;
        int i = propName.indexOf(91);
        if(i >= 0)
        {
            int k = propName.indexOf(93);
            try
            {
                index = Integer.parseInt(propName.substring(i + 1, k));
            }
            catch(NumberFormatException e) { }
            propName = propName.substring(0, i);
        }
        int j = propName.indexOf(40);
        if(j >= 0)
        {
            int k = propName.indexOf(41);
            try
            {
                key = propName.substring(j + 1, k);
            }
            catch(IndexOutOfBoundsException e) { }
            propName = propName.substring(0, j);
        }
        if(target instanceof DynaBean)
        {
            DynaClass dynaClass = ((DynaBean)target).getDynaClass();
            DynaProperty dynaProperty = dynaClass.getDynaProperty(propName);
            if(dynaProperty == null)
                return;
            type = dynaProperty.getType();
        } else
        {
            PropertyDescriptor descriptor = null;
            try
            {
                descriptor = PropertyUtils.getPropertyDescriptor(target, name);
                if(descriptor == null)
                    return;
            }
            catch(NoSuchMethodException e)
            {
                return;
            }
            type = descriptor.getPropertyType();
            if(type == null)
            {
                if(log.isTraceEnabled())
                    log.trace("    target type for property '" + propName + "' is null, so skipping ths setter");
                return;
            }
        }
        if(log.isTraceEnabled())
            log.trace("    target propName=" + propName + ", type=" + type + ", index=" + index + ", key=" + key);
        if(index >= 0)
        {
            Converter converter = ConvertUtils.lookup(type.getComponentType());
            if(converter != null)
            {
                log.trace("        USING CONVERTER " + converter);
                value = converter.convert(type, value);
            }
            try
            {
                PropertyUtils.setIndexedProperty(target, propName, index, value);
            }
            catch(NoSuchMethodException e)
            {
                throw new InvocationTargetException(e, "Cannot set " + propName);
            }
        } else
        if(key != null)
        {
            try
            {
                PropertyUtils.setMappedProperty(target, propName, key, value);
            }
            catch(NoSuchMethodException e)
            {
                throw new InvocationTargetException(e, "Cannot set " + propName);
            }
        } else
        {
            Converter converter = ConvertUtils.lookup(type);
            if(converter != null)
            {
                log.trace("        USING CONVERTER " + converter);
                value = converter.convert(type, value);
            }
            try
            {
                PropertyUtils.setSimpleProperty(target, propName, value);
            }
            catch(NoSuchMethodException e)
            {
                throw new InvocationTargetException(e, "Cannot set " + propName);
            }
        }
    }

Answer 4

public static Map describe(Object bean)
        throws IllegalAccessException, InvocationTargetException, NoSuchMethodException
    {
        if(bean == null)
            return new HashMap();
        if(log.isDebugEnabled())
            log.debug("Describing bean: " + bean.getClass().getName());
        Map description = new HashMap();
        if(bean instanceof DynaBean)
        {
            DynaProperty descriptors[] = ((DynaBean)bean).getDynaClass().getDynaProperties();
            for(int i = 0; i < descriptors.length; i++)
            {
                String name = descriptors[i].getName();
                description.put(name, getProperty(bean, name));
            }        } else
        {
            PropertyDescriptor descriptors[] = PropertyUtils.getPropertyDescriptors(bean);
            for(int i = 0; i < descriptors.length; i++)
            {
                String name = descriptors[i].getName();
                if(descriptors[i].getReadMethod() != null)
                    description.put(name, getProperty(bean, name));
            }        }
        return description;
    }    public static String[] getArrayProperty(Object bean, String name)
        throws IllegalAccessException, InvocationTargetException, NoSuchMethodException
    {
        Object value = PropertyUtils.getProperty(bean, name);
        if(value == null)
            return null;
        if(value instanceof Collection)
        {
            ArrayList values = new ArrayList();
            for(Iterator items = ((Collection)value).iterator(); items.hasNext();)
            {
                Object item = items.next();
                if(item == null)
                    values.add((String)null);
                else
                    values.add(item.toString());
            }            return (String[])values.toArray(new String[values.size()]);
        }
        if(value.getClass().isArray())
        {
            int n = Array.getLength(value);
            String results[] = new String[n];
            for(int i = 0; i < n; i++)
            {
                Object item = Array.get(value, i);
                if(item == null)
                    results[i] = null;
                else
                    results[i] = item.toString();
            }            return results;
        } else
        {
            String results[] = new String[1];
            results[0] = value.toString();
            return results;
        }
    }    public static String getIndexedProperty(Object bean, String name)
        throws IllegalAccessException, InvocationTargetException, NoSuchMethodException
    {
        Object value = PropertyUtils.getIndexedProperty(bean, name);
        return ConvertUtils.convert(value);
    }    public static String getIndexedProperty(Object bean, String name, int index)
        throws IllegalAccessException, InvocationTargetException, NoSuchMethodException
    {
        Object value = PropertyUtils.getIndexedProperty(bean, name, index);
        return ConvertUtils.convert(value);
    }    public static String getMappedProperty(Object bean, String name)
        throws IllegalAccessException, InvocationTargetException, NoSuchMethodException
    {
        Object value = PropertyUtils.getMappedProperty(bean, name);
        return ConvertUtils.convert(value);
    }    public static String getMappedProperty(Object bean, String name, String key)
        throws IllegalAccessException, InvocationTargetException, NoSuchMethodException
    {
        Object value = PropertyUtils.getMappedProperty(bean, name, key);
        return ConvertUtils.convert(value);
    }    public static String getNestedProperty(Object bean, String name)
        throws IllegalAccessException, InvocationTargetException, NoSuchMethodException
    {
        Object value = PropertyUtils.getNestedProperty(bean, name);
        return ConvertUtils.convert(value);
    }    public static String getProperty(Object bean, String name)
        throws IllegalAccessException, InvocationTargetException, NoSuchMethodException
    {
        return getNestedProperty(bean, name);
    }    public static String getSimpleProperty(Object bean, String name)
        throws IllegalAccessException, InvocationTargetException, NoSuchMethodException
    {
        Object value = PropertyUtils.getSimpleProperty(bean, name);
        return ConvertUtils.convert(value);
    }    public static void populate(Object bean, Map properties)
        throws IllegalAccessException, InvocationTargetException
    {
        if(bean == null || properties == null)
            return;
        if(log.isDebugEnabled())
            log.debug("BeanUtils.populate(" + bean + ", " + properties + ")");
        for(Iterator names = properties.keySet().iterator(); names.hasNext();)
        {
            String name = (String)names.next();
            if(name != null)
            {
                Object value = properties.get(name);
                setProperty(bean, name, value);
            }
        }    }

Answer 5

是actionservlet的源代码吗?在什么目录能看到?能大概说一下程序过程吗?谢谢

Answer 6

是通过BeanUtils类实现.具体可以看一下<<struts in action>>

Answer 7

直接下载 struts 的源代码看！ActionServlet.java

Answer 8

呵呵，就是不想直接去看那个东东,想听听各位高手消化STRUTS源码后的看法