FreeMarker代码分析（2）

FreeMarker代码分析（2）

2021SC@SDUSC

**内容非常主观，可能出现错漏，慎重参考

此部分是_DelayedConversionToString以及其子类，对各类string进行处理。

_DelayedConversionToString.java

package freemarker.core;


public abstract class _DelayedConversionToString {

    private static final String NOT_SET = new String();

    private Object object;
    private volatile String stringValue = NOT_SET;

    public _DelayedConversionToString(Object object) {
        this.object = object;
    }

    @Override
    public String toString() {
        String stringValue = this.stringValue;
        if (stringValue == NOT_SET) {
            synchronized (this) {
                stringValue = this.stringValue;
                if (stringValue == NOT_SET) {
                    stringValue = doConversion(object);
                    this.stringValue = stringValue; 
                    this.object = null;
                }
            }
        }
        return stringValue;
    }

    protected abstract String doConversion(Object obj);

}

_DelayedConversionToString重写了toString方法，当stringValue未设定值时，使全局变量stringValue = this.stringValue。

_DelayedAOrAn.java

package freemarker.core;


public class _DelayedAOrAn extends _DelayedConversionToString {

    public _DelayedAOrAn(Object object) {
        super(object);
    }

    @Override
    protected String doConversion(Object obj) {
        String s = obj.toString();
        return _MessageUtil.getAOrAn(s) + " " + s;
    }

}

_DelayedAOrAn是_DelayedConversionToString的子类

_DelayedFTLTypeDescription.java

package freemarker.core;

import freemarker.template.TemplateModel;
import freemarker.template.utility.ClassUtil;


public class _DelayedFTLTypeDescription extends _DelayedConversionToString {
    
    public _DelayedFTLTypeDescription(TemplateModel tm) {
        super(tm);
    }

    @Override
    protected String doConversion(Object obj) {
        return ClassUtil.getFTLTypeDescription((TemplateModel) obj);
    }

}

_DelayedFTLTypeDescription是_DelayedConversionToString的子类，对TemplateModel进行处理

_DelayedGetCanonicalForm.java

package freemarker.core;



public class _DelayedGetCanonicalForm extends _DelayedConversionToString {
    
    public _DelayedGetCanonicalForm(TemplateObject obj) {
        super(obj);
    }

    @Override
    protected String doConversion(Object obj) {
        try {
            return ((TemplateObject) obj).getCanonicalForm();
        } catch (Exception e) {
            return "{Error getting canonical form}";
        }
    }

}

_DelayedGetCanonicalForm是_DelayedConversionToString的子类，

_DelayedGetMessage.java

package freemarker.core;


public class _DelayedGetMessage extends _DelayedConversionToString {

    public _DelayedGetMessage(Throwable exception) {
        super(exception);
    }

    @Override
    protected String doConversion(Object obj) {
        final String message = ((Throwable) obj).getMessage();
        return message == null || message.length() == 0 ? "[No exception message]" : message;
    }
    
}

_DelayedGetMessageWithoutStackTop.java

package freemarker.core;

import freemarker.template.TemplateException;


public class _DelayedGetMessageWithoutStackTop extends _DelayedConversionToString {

    public _DelayedGetMessageWithoutStackTop(TemplateException exception) {
        super(exception);
    }

    @Override
    protected String doConversion(Object obj) {
        return ((TemplateException) obj).getMessageWithoutStackTop();
    }
    
}

_DelayedJoinWithComma.java

package freemarker.core;


public class _DelayedJoinWithComma extends _DelayedConversionToString {

    public _DelayedJoinWithComma(String[] items) {
        super(items);
    }

    @Override
    protected String doConversion(Object obj) {
        String[] items = (String[]) obj;
        
        int totalLength = 0;
        for (int i = 0; i < items.length; i++) {
            if (i != 0) totalLength += 2;
            totalLength += items[i].length();
        }
        
        StringBuilder sb = new StringBuilder(totalLength);
        for (int i = 0; i < items.length; i++) {
            if (i != 0) sb.append(", ");
            sb.append(items[i]);
        }
        
        return sb.toString();
    }

}

_DelayedJQuote.java

package freemarker.core;

import freemarker.template.utility.StringUtil;


public class _DelayedJQuote extends _DelayedConversionToString {

    public _DelayedJQuote(Object object) {
        super(object);
    }

    @Override
    protected String doConversion(Object obj) {
        return StringUtil.jQuote(_ErrorDescriptionBuilder.toString(obj));
    }

}

_DelayedOrdinal.java

package freemarker.core;


public class _DelayedOrdinal extends _DelayedConversionToString {

    public _DelayedOrdinal(Object object) {
        super(object);
    }

    @Override
    protected String doConversion(Object obj) {
        if (obj instanceof Number) {
            long n = ((Number) obj).longValue();
            if (n % 10 == 1 && n % 100 != 11) {
                return n + "st";
            } else if (n % 10 == 2 && n % 100 != 12) {
                return n + "nd";
            } else if (n % 10 == 3 && n % 100 != 13) {
                return n + "rd";
            } else {
                return n + "th";
            }
        } else {
            return "" + obj;
        }
    }
    
}

_DelayedShortClassName.java

package freemarker.core;

import freemarker.template.utility.ClassUtil;

public class _DelayedShortClassName extends _DelayedConversionToString {

    public _DelayedShortClassName(Class pClass) {
        super(pClass);
    }

    @Override
    protected String doConversion(Object obj) {
        return ClassUtil.getShortClassName((Class) obj, true);
    }

}

_DelayedToString.java

package freemarker.core;

public class _DelayedToString extends _DelayedConversionToString {

    public _DelayedToString(Object object) {
        super(object);
    }

    public _DelayedToString(int object) {
        super(Integer.valueOf(object));
    }
    
    @Override
    protected String doConversion(Object obj) {
        return String.valueOf(obj);
    }
    
}