http断点续传简单实现（java)

/* ?lb1K'(  
**SiteFileFetch.java
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*/ h<*l=`#  
package NetFox; xZ@H{):  
import java.io.*; b?oT|@  
import java.net.*; VEd#LSh  
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public class SiteFileFetch extends Thread { Do(7LidC5  
{e2 (  
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SiteInfoBean siteInfoBean = null; //文件信息Bean -p>KFHj6  
long[] nStartPos; //开始位置 1!\!3xaV  
long[] nEndPos; //结束位置 )J_!ZpMC  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 rsfA.o  
long nFileLength; //文件长度 jh]wHG  
boolean bFirst = true; //是否第一次取文件 OgrUP  
boolean bStop = false; //停止标志 vj
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File tmpFile; //文件下载的临时信息 Cc]s94  
DataOutputStream output; //输出到文件的输出流 ,"PwNv  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） _]tR1T5e  
public SiteFileFetch(SiteInfoBean bean) throws IOException w;' F;j~  
{ ;,'!  
siteInfoBean = bean; /-$`GT?l  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); Fm-W@  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 3h"; 2  
if(tmpFile.exists ()) O6;>]/`  
{  | qHWM  
bFirst = false; $BE^'5G&4Y  
read_nPos(); 8N6a=[fv<  
} ^lu)'z%6  
else AnPm5i.  
{ -p ) l63  
nStartPos = new long[bean.getNSplitter()]; O6OP{sb  
nEndPos = new long[bean.getNSplitter()]; yQhrPw> m  
} a-Cp"pKlVY  
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} SBjtg@:G0n  
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public void run() `+B+RQl}[  
{ 9;Wz;p  
//获得文件长度 qB]z"Hfq,  
//分割文件 p`1d'n[  
//实例FileSplitterFetch |gxU;"2`5~  
//启动FileSplitterFetch线程 Xk]5*C]6<  
//等待子线程返回 W\U zw,vI  
try{ Lj(hk@  
if(bFirst) )dF(5,y)  
{ 35RH|ci&  
nFileLength = getFileSize(); NfR,m]  
if(nFileLength == -1) 8+gx?pb  
{ v.6"<nT2  
System.err.println("File Length is not known!"); =]xNpX)  
} <$Uj ~jN  
else if(nFileLength == -2) :`3b|u=KZ  
{ #TW$J/Jb  
System.err.println("File is not access!"); 9z'</tJ`  
} lbg6n:@  
else ~JLqx/[|s  
{ cw"x0 RS  
for(int i=0;i<nStartPos.length;i++) ![abDT5![  
{ {,APZ`q|  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); c#"\&~. P  
} N>ct`a)BD/  
for(int i=0;i<nEndPos.length-1;i++) 
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{ !kASEjFz|f  
nEndPos = nStartPos[i+1]; .&@|)u  
} mSwOP  
nEndPos[nEndPos.length-1] = nFileLength; y13=y}dyDH  
} l`I]eTo)^  
} {k
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//启动子线程 x0lX6 |D  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; U%k e5uwP  
for(int i=0;i<nStartPos.length;i++) `Q(ac| 0  
{ Q^MB%L;D  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), ?783LBe  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), wmo'Pl  
nStartPos,nEndPos,i);  QV .A.DK  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); &@+K%qW[e  
fileSplitterFetch.start(); gP(-Op  
} @/$mZ]|T  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), RX2= iO"  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); "bf8[D  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", n+Ag|.,|  
nEndPos = " + nFileLength); <*(~x esPS  
// fileSplitterFetch[nPos.length-1].start(); p+8]H %  
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f6|3| +  
//等待子线程结束 iU%Gvf^?'5  
//int count = 0; HENCQ_Wra  
//是否结束while循环 sM5 w~R>Y  
boolean breakWhile = false; ^G2vA8%  
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while(!bStop) "apv)xdW  
{ KG3*~G  
write_nPos(); =JVRm 2#*  
Utility.sleep(500); IB!Wrnj?  
breakWhile = true; (ZEVbAY?i  
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for(int i=0;i<nStartPos.length;i++) `=KrV#/758  
{ [qZ4+xF,,  
if(!fileSplitterFetch.bDownOver) b%PVF&C9W  
{ }?fa+FQGp  
breakWhile = false; ~36c0 =  
break; *(>$4$9
n  
} ]oya<C6pR  
} @nc!(P7_  
if(breakWhile) \3LD^[qi  
break; "5y^s!/  
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//count++; !k s<VJh  
//if(count>4) vy#c(:UQR  
// siteStop(); $`=?Nb@@#  
} YKx0Zs  
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hPk+vvXtK  
System.err.println("文件下载结束！"); .86..1  
} A.h?#%TLL  
catch(Exception e){e.printStackTrace ();} Xj@Kt|&`k  
} ]yIy~V  
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//获得文件长度 [KE4wz+s{  
public long getFileSize() BuvBSLC~  
{ u?J(l)gd  
int nFileLength = -1; CD tYj  
try{ Q-au)R,  
URL url = new URL(siteInfoBean.getSSiteURL()); &qpA<F@7  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 3
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httpConnection.setRequestProperty("User-Agent","NetFox"); 8/F2V?iT  
R|M:6]}   
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int responseCode=httpConnection.getResponseCode(); C {,d4KG  
if(responseCode>=400) MnS"M[y3  
{ (,TO|  
processErrorCode(responseCode); f7W=x6Z4  
return -2; //-2 represent access is error C`#N Q*O  
} }GC{~ SZ4  
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String sHeader; ibAA:I,d  
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for(int i=1;;i++) wS^-o  
{ v6n(<0:  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); T*ic?!  
//Utility.log(in.readLine()); c"$_V[m  
sHeader=httpConnection.getHeaderFieldKey(i); A+l"  
if(sHeader!=null) s-ou;S3s  
{ A^Zs?<C-  
if(sHeader.equals("Content-Length")) &p%ctg  
{ +OH."4Z  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); V&nN/CF  
break; .=FJ5?:4i%  
} #Nd+X@j  
} z7_./ksQ  
else jl@8pO$  
break; <>:kAT,sP  
} z[rB/|2  
} o99 a=x6  
catch(IOException e){e.printStackTrace ();} *o#`lH  
catch(Exception e){e.printStackTrace ();} \wCL)t.cX  
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Utility.log(nFileLength); [KKo
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return nFileLength; :Rn9rdX  
} xle29:?l  
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//保存下载信息（文件指针位置） =3:ltI.'*I  
private void write_nPos() A^7!+1*K+  
{ 6{~I7!m"  
try{ f1{ckHAY55  
output = new DataOutputStream(new FileOutputStream(tmpFile)); l*u@T|Fc$  
output.writeInt(nStartPos.length); <f6Oj`{f4  
for(int i=0;i<nStartPos.length;i++) O`=Uq0Vv  
{ FdqUv%(Em  
// output.writeLong(nPos); k?#6j1pn  
output.writeLong(fileSplitterFetch.nStartPos); 40E[cGz$*  
output.writeLong(fileSplitterFetch.nEndPos); HHYcFoJwYN  
} Kv7NCpq'  
output.close(); O?!"15  
} %'HUC>ChN  
catch(IOException e){e.printStackTrace ();} >']H)c'2  
catch(Exception e){e.printStackTrace ();} 9<ayQ*  
} 7ou^wt+%  
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//读取保存的下载信息（文件指针位置） _6' g]4  
private void read_nPos() .<B1i  
{ 'zb7:[[7%  
try{ a?kQ2<@g  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); uz#9w\="  
int nCount = input.readInt(); cPbz7  
nStartPos = new long[nCount]; ZS+2.)A  
nEndPos = new long[nCount]; q|l|gY1g)  
for(int i=0;i<nStartPos.length;i++) ^bG!k]U!2  
{ +9X[gef8  
nStartPos = input.readLong(); )3AT=b  
nEndPos = input.readLong(); i@* ^]'
  
} 9& j]  
input.close();
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} S(6ZX>wv:  
catch(IOException e){e.printStackTrace ();} "ir*;|  
catch(Exception e){e.printStackTrace ();} EHZSM5hu  
} n3N"Ax  
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private void processErrorCode(int nErrorCode) 8(}sZ)6  
{ *`#,^p`j b  
System.err.println("Error Code : " + nErrorCode); TRZ^$<AG  
} vF&b|V+,  
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//停止文件下载 U6Ak"  
public void siteStop() ThxrhQ q[+  
{ &; \v_5N6  
bStop = true; bnGA.b  
for(int i=0;i<nStartPos.length;i++) ho1F8TG=  
fileSplitterFetch.splitterStop(); b5Pn|5AVj  
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} (4LLTf0  
} 8;8}Oq  
//负责部分文件的抓取 d3GK.8y_z  
**FileSplitterFetch.java meR2"JN'  
*/ MlFvDy  
package NetFox; jGn^
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import java.io.*; 3U)8P6Fz  
import java.net.*; "tM/`:Qp  
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public class FileSplitterFetch extends Thread { kP$gl|  
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String sURL; //File URL F6p1 VFs  
long nStartPos; //File Snippet Start Position {%{GZ  
long nEndPos; //File Snippet End Position cAS_?"V a  
int nThreadID; //Thread's ID 0K ?(xB  
boolean bDownOver = false; //Downing is over sFK<:ka  
boolean bStop = false; //Stop identical DOe
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FileAccessI fileAccessI = null; //File Access interface y6}):|  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException {M/c!
  
{ E,7~kd~y`  
this.sURL = sURL; T;@>O^  
this.nStartPos = nStart; ]'(7T#  
this.nEndPos = nEnd; rzDJH:W{2  
nThreadID = id; 4&e@>  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 |@.<}/  
} BA,6f?ktXS  
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public void run() 7-I>53@  
{ VU9P\|c@<  
while(nStartPos < nEndPos && !bStop) v\,%)Z/  
{ yipD5,TC  
.5;LL,S-  
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try{ sG2 3[t8  
URL url = new URL(sURL); 5Q`n6x|  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection ();
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httpConnection.setRequestProperty("User-Agent","NetFox"); -P>=WZu  
String sProperty = "bytes="+nStartPos+"-"; :-La $I>  
httpConnection.setRequestProperty("RANGE",sProperty); fhKiG%i'l  
Utility.log(sProperty); .To:tN#  
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InputStream input = httpConnection.getInputStream(); .A)Un/k7  
//logResponseHead(httpConnection); v&2@<I>  
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byte[] b = new byte[1024]; t<F]%8S  
int nRead; #J724`  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) ]31XX=  
{ Xe;(y "pR  
nStartPos += fileAccessI.write(b,0,nRead); -WvgK"k  
//if(nThreadID == 1) 
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// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); S.|kg2  
} (M,VwwN  
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Utility.log("Thread " + nThreadID + " is over!"); o MkY#<Q}  
bDownOver = true; 3n(gfQo-o  
//nPos = fileAccessI.write (b,0,nRead); ggc?J<Dv  
} w/5^R  
catch(Exception e){e.printStackTrace ();} D"4&9"CU  
} V9u\;5oL  
} 9zYiG3 d  
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//打印回应的头信息 @[tV_Z%,b  
public void logResponseHead(HttpURLConnection con) 8sIA;r%S  
{ AAq=,=:R<  
for(int i=1;;i++) F(9 Y/UXH  
{ .*-w UBr  
String header=con.getHeaderFieldKey(i); B36puz 0{  
if(header!=null) OP`Jc$|6  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ?%/u/*9rj  
Utility.log(header+" : "+con.getHeaderField(header)); X2dc\v.x  
else ^y0C5Bl;  
break; [Cj)@OC  
} ?7MwTi8{F  
} tQ/ #t<4D  
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public void splitterStop() ct4 [b|  
{ i4zV
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bStop = true; Qy5Os?9"  
} D?yE$_3>c  
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|\|)j>[i  
} b>=Wq  
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/* 6w"( y~c1  
**FileAccess.java @D~+D@i$TW  
*//文件访问(定位，写) 'nWs0iH.  
package NetFox; 9/1+BQ  
import java.io.*; p^igscPF6  
$@_t5?n``F  
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public class FileAccessI implements Serializable{ (;pi"/x[  
M?xpwqu\  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 PN"8 Y  
RandomAccessFile oSavedFile; ,{{#a*nd  
long nPos; QhXC>)PW  
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public FileAccessI() throws IOException /ggkb8<3  
{ Bug}^t{M  
this("",0); YYE8/\+B.  
} Z@,PZ  
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public FileAccessI(String sName,long nPos) throws IOException twtkH~`"Q  
{ O5qW*r'  
oSavedFile = new RandomAccessFile(sName,"rw"); %x}&=zx0*1  
this.nPos = nPos; l{6` k<J(  
oSavedFile.seek(nPos); =,4 '"  
} YWRE
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w=D%D8 r2  
UV']NHh  
public synchronized int write(byte[] b,int nStart,int nLen) lH)em.#  
{ #~4{`]W6
  
int n = -1; vXWsF\g  
try{ slge+xq\J  
oSavedFile.write(b,nStart,nLen); %l:|2s:  
n = nLen; M
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} =@JS88+  
catch(IOException e) n</k/Mk}  
{ qcTmsMpj  
e.printStackTrace (); c.(Ud`jc  
} ZD)0P=%  
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return n; X
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} B:?#l=FL  

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} QJ#u[hsMFp  
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/* -@ZzG uS(  
**SiteInfoBean.java =a)iVXSB]  
*/ Iz}2 ^  
package NetFox; +urS5c* j  
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public class SiteInfoBean { Kc%n(,+%"  
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private String sSiteURL; //Site's URL ua`6M  
private String sFilePath; //Saved File's Path l:Dn3Q  
private String sFileName; //Saved File's Name k,,!P""  
private int nSplitter; //Count of Splited Downloading File 731h ~x!u  
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Vk-W8[W 7  
public SiteInfoBean() ~reQV6oQua  
{//nSplitter的缺省值为5 -F"d0a,  
//default value of nSplitter is 5 / R_ u\?k(  
this("","","",5); ;TL(w7vK  
} 0)d?Y  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) _0,"vFdj  
{ 8 7RHA $?  
sSiteURL= sURL; 7qP4B9S  
sFilePath = sPath; oGm1d{_-O  
sFileName = sName; e0f":Vct  
this.nSplitter = nSpiltter; >ik1]!j]Lv  
]3L@$`ys  
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} h/I@_?k+  
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public String getSSiteURL() ^^G-kg  
{ .OmQ'  
return sSiteURL; ?k{|Lk  
} L5Urg*GNL  
@Q;i.u{V  
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public void setSSiteURL(String value) QXdaMc+Ck  
{ "r8EC  
sSiteURL = value; +XEjXH5K  
} K`h
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public String getSFilePath() =G(*gx  
{ ~|&="K4,:  
return sFilePath; LeY+p]n~  
} q*L ]  
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public void setSFilePath(String value) |*:tyP%m^  
{ 5k69F  
sFilePath = value; RCI4~q  
} pd d|n2q  
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public String getSFileName() np\st7&f6  
{ dCE\^q[{  
return sFileName; nO~b=q
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} dM Y 0K  
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public void setSFileName(String value) t)9]<pN%  
{ [s~JceUyX  
sFileName = value; )ZGYhE  
} [-\({<t3x  
25d\!3#E  
"Y7+{  
public int getNSplitter() {AOG"T&<  
{ f'&GFL=c  
return nSplitter; .eo~?u<j&  
} ^IBGYl5n  

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public void setNSplitter(int nCount) %JQ~!3  
{ Va7c#P?  
nSplitter = nCount; ~LbS~_\C=  
} z!$gVWG  
} gmY/STN   
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/* ~\$=w10  
**Utility.java AYcgi  
*/ .U9R>#  
package NetFox; D9.`hs0  
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public class Utility { ahA{B1M)n  
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public Utility() eIg+PuQD]  
{ f])M04<  
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} T"?Y5t`(  
jv =EheD  
//线程睡眠 !EOQhh  
public static void sleep(int nSecond) 
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{ G}VDEC  
try{ o@9+mM"B)  
Thread.sleep(nSecond); g:_hj_1Y M  
} ;1 |x  
catch(Exception e) ~^&R#4J  
{ II;Te7~  
e.printStackTrace (); ~.Cv DJy  
} HY;9?KJ'  
} o)&"Rf  
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//日志 3pSj kS|?>  
public static void log(String sMsg) H<`\bej,  
{ &vkjmiAS  
System.err.println(sMsg); ;L~p|sF  
} }3Y <$YL"R  
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(WRMaI72(  
public static void log(int sMsg) Fu7M0X'p  
{ ;F5"}x  
System.err.println(sMsg); R)oB!$k  
} S/4r\6  
} @vRwzc\  
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/* zrRFn `B  
**TestMethod.java *}cSE|S%  
*/ #f{lC0~vA  
package NetFox; :+ Jt^ 6  
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public class TestMethod { +;Cr];b3  
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public TestMethod() ;+U<bqL6  
{ ///xx/weblogic60b2_win.exe 0{+.H_f`  
try{ +q{[\#t5  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); Vr=OYI'A  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); PD6_)PXn  
SiteFileFetch fileFetch = new SiteFileFetch(bean); raE Mm  
fileFetch.start(); 19c@`?  
} V.6)0fKZW  
catch(Exception e){e.printStackTrace ();} hJ*Ihwn|  
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} q0&$7GH4  
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public static void main(String[] args) `Ye8 Q5v"]  
{ 'T,c.Vj)  
new TestMethod(); h
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} G.\l qYrXU  
} 6w|J-{2  
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