http断点续传简单实现（java)

/* QZJnb%]  
**SiteFileFetch.java .\:MB7p  
*/ N~P1^x~  
package NetFox; :q~5Xw/  
import java.io.*; VAA="
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import java.net.*; FSkLR h  
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public class SiteFileFetch extends Thread { '7g]@Q7  
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SiteInfoBean siteInfoBean = null; //文件信息Bean _jH./ @G  
long[] nStartPos; //开始位置 iUs_)1  
long[] nEndPos; //结束位置 Y$9x!kV  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 "\u<\CL  
long nFileLength; //文件长度 mY]o_\`  
boolean bFirst = true; //是否第一次取文件 cPkP/3I]h  
boolean bStop = false; //停止标志 S VypR LVB  
File tmpFile; //文件下载的临时信息 G8'  
DataOutputStream output; //输出到文件的输出流 ab`9MJc;  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类）  FL b  
public SiteFileFetch(SiteInfoBean bean) throws IOException *S?'[PS]1  
{ u8gqWsvruM  
siteInfoBean = bean; O:ACp<@  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); "{kE#`c6<n  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); "{Hl! Zq/  
if(tmpFile.exists ()) pu_?)U  
{ KGc
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bFirst = false; cj[x%eK>  
read_nPos(); smn~p/u  
} B>c2 *+Bk  
else Q(O0z3b  
{ Tp.:2[  
nStartPos = new long[bean.getNSplitter()]; .m.
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nEndPos = new long[bean.getNSplitter()]; O8Z+g{  
} Ai)>ot  
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} nw#AKtd@x  
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public void run() ) I(9qt>Y  
{ XA
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//获得文件长度 HU$]o
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//分割文件 F'CJN$6Mw/  
//实例FileSplitterFetch 5,-:31(j\  
//启动FileSplitterFetch线程 MNp4=R  
//等待子线程返回 AMASh*  
try{ JSID@ n<b?  
if(bFirst) *IIA"tC  
{ ju
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nFileLength = getFileSize(); &%g$Bi,G  
if(nFileLength == -1) YT,yRV9#  
{ *rB@[(/  
System.err.println("File Length is not known!"); 1K(mdL{m5  
} PF#<CF$=  
else if(nFileLength == -2) 0|C !n+OK  
{ fs-LaV 0  
System.err.println("File is not access!"); bdfs'udt9  
} R0mkEM  
else lr?SL\D  
{ 2R,8q0qR:  
for(int i=0;i<nStartPos.length;i++) sLFZ61rT  
{ M8$eMS1  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ,*YmXR-"  
} 3,2$Ny3N  
for(int i=0;i<nEndPos.length-1;i++) ~gHn>]S0  
{ P00%EB  
nEndPos = nStartPos[i+1]; G/#m.=t  
} Vbe@S?u-  
nEndPos[nEndPos.length-1] = nFileLength; qz2`%8}F)  
} n5;@}Rai  
} Ni|MTE]~  
*e<}hmDr  
m*YfbOhs#  
//启动子线程 FBvh7D.hV  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; \S1W,H|  
for(int i=0;i<nStartPos.length;i++) sKJr34  
{ 0-;>O|U3  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), =vvd)og  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), t0r0{:  
nStartPos,nEndPos,i); +@yU `  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); g-B{K "z  
fileSplitterFetch.start(); g^x=y  
} ^2{6W6=  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), G e5Yz.Qv  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); l)~U8  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", lw99{y3<<  
nEndPos = " + nFileLength); E'98JZ5ga  
// fileSplitterFetch[nPos.length-1].start(); (y~%6o6  
)=`
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//等待子线程结束
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//int count = 0; >Vg [A  
//是否结束while循环 {`e-%<  
boolean breakWhile = false; 7a^D[f0V  
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LI&E.(:  
while(!bStop) 3 S*KjY'@  
{ *SIYZE'  
write_nPos(); Vh2uzG  
Utility.sleep(500); >B=s+}/ME  
breakWhile = true; 7l[@c|e  
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for(int i=0;i<nStartPos.length;i++) )?7/fF)@|  
{ H1L)9oa  
if(!fileSplitterFetch.bDownOver) VH<d[Mj  
{ WPAUY<6f  
breakWhile = false; ;\6@s3  
break; kPiY|EH  
} mEu2@3^E }  
} ]
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if(breakWhile) i*$~uuY  
break; NZa 7[}H  
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//count++; cruBJZr*  
//if(count>4) ~d1=_p:~T  
// siteStop(); x X[WX#'f  
} L N.:>,  
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System.err.println("文件下载结束！"); 6({)O1Z  
} Nnr[@^M5  
catch(Exception e){e.printStackTrace ();} "Nb2[R  
} Y .cjEeL@  
6 C O5:\  
9nY|S{L  
//获得文件长度 B$YoglEW:  
public long getFileSize() rx 74v!  
{ 'DNxc  
int nFileLength = -1; IVZUB*wv)b  
try{ >)='.aR<  
URL url = new URL(siteInfoBean.getSSiteURL()); <8Tp]1z  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); (aC=,5
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httpConnection.setRequestProperty("User-Agent","NetFox"); 8_G6X\q};  
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%'_:#!9  
int responseCode=httpConnection.getResponseCode(); KdYR?rY  
if(responseCode>=400) &0\:MJc  
{ 0#Pa;(  
processErrorCode(responseCode); .VNz(s  
return -2; //-2 represent access is error SZLugyZ2Y  
} m@+QC$6S  
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String sHeader; 27+faR  
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for(int i=1;;i++) a^|9rho<  
{ qyFeq])  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); b_6c
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//Utility.log(in.readLine()); 7FyE?  
sHeader=httpConnection.getHeaderFieldKey(i); )=X g  
if(sHeader!=null) MffCk!]  
{ [tJn!cMs  
if(sHeader.equals("Content-Length")) tU2#Z=a  
{ 'J-a2oiM(  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); m;hp1VO)  
break; &+A78I   
} ks6iy}f7  
} n1JV)4Mv  
else G4P*U3&p  
break; 3**t'iWQ  
} >o{JG(Rn  
} 4e.19H9  
catch(IOException e){e.printStackTrace ();} E`(=n(Qu  
catch(Exception e){e.printStackTrace ();} =
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Utility.log(nFileLength); ^BRqsVw9  
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return nFileLength; lw}7kp4 2F  
} ER~RBzp  
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//保存下载信息（文件指针位置） C96*,.j~'  
private void write_nPos() 0A~UuH0.  
{ 3(|,:"9g  
try{ (3D&GY!/  
output = new DataOutputStream(new FileOutputStream(tmpFile)); Ab/JCZNn  
output.writeInt(nStartPos.length); 0gW{6BtPWm  
for(int i=0;i<nStartPos.length;i++) 3h>L0  
{ H~vrCi~t"  
// output.writeLong(nPos); %,z;W-#gnY  
output.writeLong(fileSplitterFetch.nStartPos); 4%8den,|  
output.writeLong(fileSplitterFetch.nEndPos); ?E+f<jol  
} rO.[/#p\  
output.close(); ]Q0bL  
} %xG
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catch(IOException e){e.printStackTrace ();} 4vN:Kj  
catch(Exception e){e.printStackTrace ();} 4ytdcb   
} bEmN tp^  
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//读取保存的下载信息（文件指针位置） 9kF0H a}J  
private void read_nPos() l4U*Lv>   
{ 4lc|~Fj++  
try{ GH-Fqz  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); P7,g^:$  
int nCount = input.readInt(); Br}@Vvq@  
nStartPos = new long[nCount]; 9_jiUZFje  
nEndPos = new long[nCount]; M
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for(int i=0;i<nStartPos.length;i++) o3|4PAA/  
{ X<Cfy  
nStartPos = input.readLong(); s !2Iui @  
nEndPos = input.readLong(); NyRa.hgZ;  
} Hd\oV^>  
input.close(); qwJp&6  
} w|S b`eR  
catch(IOException e){e.printStackTrace ();} #|(>UM
\  
catch(Exception e){e.printStackTrace ();} Z : xb8]y  
} x*'H@!!G  
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private void processErrorCode(int nErrorCode) Wu|MNB?M  
{ X
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System.err.println("Error Code : " + nErrorCode); KN657 |f  
} 'NCqI  
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& C)
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//停止文件下载 ,lvG5B\0  
public void siteStop() %dW;P[0  
{ uQx/o^  
bStop = true; T*0;3&sA  
for(int i=0;i<nStartPos.length;i++) Keo<#Cc?  
fileSplitterFetch.splitterStop(); b/R7Mk1  
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} aZ_3@I{d`  
} aN07\  
//负责部分文件的抓取 lkJxb~S  
**FileSplitterFetch.java ,K\7y2/  
*/ %]0?vw:;j  
package NetFox; `|Di?4+6%  
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import java.io.*; c?_7e9}2  
import java.net.*; 2#^g] o-N  
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public class FileSplitterFetch extends Thread { ^JMG'@x  
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String sURL; //File URL EwV$2AK  
long nStartPos; //File Snippet Start Position H,GjPIG  
long nEndPos; //File Snippet End Position ,C><n kx  
int nThreadID; //Thread's ID \a|~#N3?  
boolean bDownOver = false; //Downing is over L YB@L06a  
boolean bStop = false; //Stop identical EZI#CLT[  
FileAccessI fileAccessI = null; //File Access interface $<2d|;7r  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 0ElEaH1z  
{ -`\^_nVC  
this.sURL = sURL; |T/OOIA=sI  
this.nStartPos = nStart; a5ZXrWv  
this.nEndPos = nEnd; ?uL-qsU  
nThreadID = id; x X3I`  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 Q[NoFZ V!  
} Ym\<@[3+!  
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public void run() 2>k*9kyp  
{ 25vjn 1$sW  
while(nStartPos < nEndPos && !bStop) (T pnJq  
{ v.C  
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try{ <2 [vR|Q*  
URL url = new URL(sURL); obF|;fwPnR  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); A~nqSe  
httpConnection.setRequestProperty("User-Agent","NetFox"); sPW:[  
String sProperty = "bytes="+nStartPos+"-"; uk$MQv*D  
httpConnection.setRequestProperty("RANGE",sProperty); H3R{+7  
Utility.log(sProperty); l]wLQqoO  
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InputStream input = httpConnection.getInputStream(); N]/cBGy  
//logResponseHead(httpConnection); Km= Y^x0  
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byte[] b = new byte[1024]; 6AY(/N8V  
int nRead; DDGDj)=`  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) \7qj hA@  
{ t(roj@!x_o  
nStartPos += fileAccessI.write(b,0,nRead); e }C,)  
//if(nThreadID == 1) *@#Gc%mGu  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); EFVZAY"+!;  
} ETU-6qFtO  
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Utility.log("Thread " + nThreadID + " is over!"); %SIll  
bDownOver = true; ?K2E
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//nPos = fileAccessI.write (b,0,nRead); t~K[`=G\ex  
} GEVDXx>@  
catch(Exception e){e.printStackTrace ();} 'do2n/  
} Uq'W<.v5  
} S{e3aqT#N  
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//打印回应的头信息 iZnLgkk@  
public void logResponseHead(HttpURLConnection con) JSju4TQ4  
{ Gchs$^1`t  
for(int i=1;;i++) ;Krs*3 s  
{ &W<9#RPK'  
String header=con.getHeaderFieldKey(i); Q~wS2f`)  
if(header!=null) J`[jub  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); wI 7gHp  
Utility.log(header+" : "+con.getHeaderField(header)); #P}n+w_@  
else |gxPuAXa)  
break; tF/Ni*\^rV  
} #=y)Wuo=  
} 7w9'xY  
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public void splitterStop() ,Il) tH  
{ ^}vf  
bStop = true; ZEDvY=@a   
} q+8de_"]  
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} 19O   
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/* s Adb0 A  
**FileAccess.java }8}`A\dgV  
*//文件访问(定位，写) kzCJs  
package NetFox; .3_u5N|[=W  
import java.io.*; ~V?z!3r-)  
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public class FileAccessI implements Serializable{ > fV"bj.  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 W-r^ME  
RandomAccessFile oSavedFile; ^4]=D nd%  
long nPos; V+lS\E.  
-"'+#9{h  
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public FileAccessI() throws IOException "S'Yn-  
{ ->;2CcpHB  
this("",0); H-e$~vEbP  
} )n9,?F#l  
( 6zu*H)  
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public FileAccessI(String sName,long nPos) throws IOException W58?t6! =  
{ G{X7;j e  
oSavedFile = new RandomAccessFile(sName,"rw"); eF7I5k4  
this.nPos = nPos;
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oSavedFile.seek(nPos); 5/U{b5  
} ~$^>Vo  
c}S<<LR  
+C7W2!I[G2  
public synchronized int write(byte[] b,int nStart,int nLen) l+y;>21sTu  
{ sb_/FE5e  
int n = -1; cg]Gt1SU  
try{ $E;Tj|W  
oSavedFile.write(b,nStart,nLen); ydY(*]  
n = nLen; rrgOp5aV
"  
} fXnewPr=#  
catch(IOException e) *a|575e< z  
{ se>\5k  
e.printStackTrace (); /L(}VJg-  
} +]wM$
bP  
g
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return n; #>G:6'r  
} /!>OWh*~  
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} AG%[?1IXW  
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+zDRed_]=_  
/* NB^Al/V@  
**SiteInfoBean.java DS@Yto  
*/ RTg\c[=w  
package NetFox; "|&3z/AUh  
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public class SiteInfoBean { UB8n,+R  
8[AU`F8W  
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private String sSiteURL; //Site's URL 2Rwd\e.z  
private String sFilePath; //Saved File's Path `) ],FE*:  
private String sFileName; //Saved File's Name sieC7raO  
private int nSplitter; //Count of Splited Downloading File E&t8nlTx  
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sEfT#$ a^8  
public SiteInfoBean() Zi\ex\ )5  
{//nSplitter的缺省值为5 z"QtP[_m  
//default value of nSplitter is 5 ~W4SFp  
this("","","",5); :?ZrD,D  
} 2$t%2>1>@  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) |Go$z3bx  
{ aTH$+f1?Q  
sSiteURL= sURL; !RwhVaSh  
sFilePath = sPath; pH3\X cn  
sFileName = sName; w03Ur4>T  
this.nSplitter = nSpiltter; WH7UJCQ  
{LA?v& b'  
q&6|uV])H  
} Rq?t=7fX)  
>P}XCAU  
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public String getSSiteURL() v}AjW%rB  
{ hc0$mit  
return sSiteURL; #E\6:UnT  
} |)&d9|
]  
5{DwD{Q  
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public void setSSiteURL(String value) X6w+L?A  
{ - 3PLP$P  
sSiteURL = value; ([rSYKpi  
} sy4Nm0m  
ld({1jpX,  
1#AxFdm
1  
public String getSFilePath() G8?Do+[  
{ 8 ?y|  
return sFilePath; #v~dhx=R  
} &dni6E4  

,(sE|B#s  
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public void setSFilePath(String value) cZoj|=3a  
{ grkA2%N  
sFilePath = value; EX, {1^h  
} -,g.39u  
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public String getSFileName() ij3W8i9'  
{ ^liW*F"UY  
return sFileName; |tLD^`bt  
} 3q@JhB  
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]WcN6|b+  
public void setSFileName(String value) w0H#M)c  
{ :1bDkoK  
sFileName = value; (@^ySiU  
} H;tE=  
\K%M.>]vq  
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public int getNSplitter() :Zob"*T  
{ 6<5:m:KE  
return nSplitter; ln,9v  
} v7#|%  
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public void setNSplitter(int nCount) o#z$LT1dY  
{ 8)"lCIf  
nSplitter = nCount; W|0))5a  
} i!RYrae  
} ;g2UIb?{6  
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/* D8Mq '$-  
**Utility.java 5.yiNWh  
*/ @k'V`ZQF  
package NetFox; ^f"|<r  
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public class Utility { ^rjUye%EK  
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public Utility() XsFzSm  
{ zA3r&stN+  
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} anfnqa8  
#&L7FBJ"*v  
//线程睡眠 \\Q){\S  
public static void sleep(int nSecond) 3=Rk(%:;  
{ CW/L(RQ  
try{ S}]B|Q  
Thread.sleep(nSecond); OZ"76|H1`  
} !g=b=YK  
catch(Exception e) s&$e}yxVO  
{ Zv-1*hhHf  
e.printStackTrace (); jWh)bsqI!  
} !)W#|sys&  
} ]Ge>S?u  
ryA+Lli.  
//日志 =d:3]M^
 
public static void log(String sMsg) ObS#aRq  
{ &uBfsa$  
System.err.println(sMsg); B8.}9  
} a+a6P5kJ  
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public static void log(int sMsg) l]&x~K}  
{ nvNF~)mu  
System.err.println(sMsg); + DE/DR:  
} 8xhx*A  
} H/;AlN|!  
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/* C>,> _  
**TestMethod.java 5tLb o  
*/ |Sua4~yL(  
package NetFox; =#<bB)59  
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8.I3%u  
public class TestMethod { r=AA /n<  
asLrXGGyT  
`s Pk:cNz~  
public TestMethod() b7T;6\[m  
{ ///xx/weblogic60b2_win.exe #)[.Xz:U  
try{ Rr[Wka9[  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); , `EOJ"|  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); C-h?#/#?y  
SiteFileFetch fileFetch = new SiteFileFetch(bean); zfg+gd)Z
 
fileFetch.start(); Zkqq<  
} X-TGrdoX  
catch(Exception e){e.printStackTrace ();} +o"CMI  
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.c__T{<)[  
} e+4Eiv  
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public static void main(String[] args) EVw{G<  
{ D<<q5gG  
new TestMethod(); Wv;,@
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} ?.lo[X<,*  
} DBLM0*B  
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